The Passage of Humaitá (Portuguese: Passagem de Humaitá) was an operation of riverine warfare during the Paraguayan War − the most lethal in South American history − in which a force of six Imperial Brazilian Navy armoured vessels was ordered to dash past under the guns of the Paraguayan fortress of Humaitá. Some competent neutral observers had considered that the feat was very nearly impossible. The purpose of the exercise was to stop the Paraguayans resupplying the fortress by river, and to provide the Empire of Brazil and its Allies with a much-needed propaganda victory. The attempt took place on 19 February 1868 and was successful – the attackers had hit upon the fortress' weakness. It restored the reputation of the Brazilian navy and the Brazilian Empire's financial credit, and caused the Paraguayans to evacuate their capital Asunción. Some authors have considered that it was the turning point or culminating event of the war. The fortress, by then fully surrounded by Allied forces on land or blockaded by water, was captured on 25 July 1868.
== Historical background == The Fortress of Humaitá was a defensive system on a bend in the River Paraguay, not far from its mouth. Long considered to be almost impregnable, it prevented enemy shipping ascending the river and hence invading the Republic of Paraguay. There may have been other routes by which the country could have been invaded, but they were considered more difficult still. From the main article on the Fortress of Humaitá it appears that Marshal-President López of Paraguay may have calculated that, because the fortress could not be bypassed except at ruinous expense, he could risk making war on the much more populous Brazil and Argentina.
The Paraguayan War (also known as the War of the Triple Alliance) of 1864–1870 was the most lethal in South American history, and − in terms of its relative mortality − very possibly the worst in modern history, anywhere. It actually commenced when López seized the Brazilian ship Marques de Olinda on her routine voyage up the River Paraguay to the Brazilian province of Mato Grosso, then sent military forces to invade the province itself. It developed further when he seized Argentine naval vessels moored in the port of Corrientes, north east Argentina. Thereafter López sent two further armies, one to invade the Argentine province of Corrientes along the River Paraná and the other to invade the Brazilian province of Rio Grande do Sul along the River Uruguay. On 1 May 1865 Brazil, Argentina and Uruguay signed the Treaty of the Triple Alliance by which they would not negotiate peace with Paraguay until the government of López had been deposed.
Further, for Brazil the river was the only practicable route to its interior province of Mato Grosso, which had been invaded by the forces of López earlier in the War. The war aims of the Allies (Brazil, Argentina and Uruguay) explicitly included the capture and destruction of Humaitá, and it was the prime military objective of the Allied high command.
The Allies' strategic problem
It took the Allies about a year to defeat the invading Paraguayan forces in the Brazilian province of Rio Grande do Sul and expel them from Argentina. According to their treaty they now had to neutralise Humaitá and depose López. In April 1866 the Allies crossed the River Paraná into southwestern Paraguay, occupying a small strip of territory. Their next strategic problem was how to proceed up the River Paraguay, getting past the Fortress of Humaitá. Briefly, the fortress of Humaitá was built on a sharp concave bend in the river and comprised more than a mile of heavy artillery batteries atop a low cliff. The channel was only 200 yards wide, and ran within easy range of the batteries; a heavy chain boom could be raised to block the navigation and detain the shipping under the guns. 'Torpedoes' (improvised contact naval mines) could be released or anchored in the stream. On its landward side the fortress was protected either by impassable terrain or by 8 miles of trenches with 120 heavy guns and a garrison of 18,000 men. An attempt to capture one of its outworks by frontal attack failed disastrously at the Battle of Curupayty (22 September 1866); another frontal attack was out of the question.
From a naval perspective the heavy guns of the fortress might – in principle – be bypassed by the latest ironclads (armoured vessels), provided the chain boom could be cut and any 'torpedoes' avoided. But those vessels could not have operated ahead of their forward bases for long, because they would need to be resupplied with fuel, ammunition and provisions. Furthermore, the Brazilian navy command claimed there was no room inside the ironclads for the conveyance of troops; the wooden transport vessels could not have accompanied them. The land operation in which the Allied land forces did succeed in capturing the Humaitá complex, known as the Siege of Humaitá, is outside the scope of this Article. However, to starve out Humaitá it was necessary to stop the Paraguayans resupplying it by river. But, in order to do that, it was necessary to obtain command of the river, in other words, to steam past Humaitá.
Difficulties facing the Allies
=== 1. The home front === By the end of 1867 the Allies were badly in need of a propaganda victory. The war had cost them a lot of men and money; though they still had superior manpower yet they were stuck in the small area of southwestern Paraguay shown in the map. The disaster of Curupayty had sunk their morale and led to a year's inactivity. And it had fostered an already strong anti-war faction in Argentina. Armed revolutions had broken out in that country – especially in the Andean provinces – demanding peace with Paraguay. It had got to the point that the Allied commander-in-chief General Bartolomé Mitre had temporarily quit Paraguay with 4,000 Argentine troops in order to put down the revolts, leaving the Brazilian General the Marquis of Caxias in charge. Brazil financed its warlike operations partly by borrowing in the financial markets especially the City of London, and advanced money to Argentina and Uruguay. The lack of progress in the war was affecting its financial credit.
In June 1867 Caxias wrote to a colleague: My friend, let us see if we can conclude this cursed war which has ruined our country, and whose duration shames us.
2. Extended lines of communication
Lengthy lines of communication vastly increased the difficulty and cost of the war for Brazil. According to the American envoy to Paraguay, López had banked on that fact when deciding to make war on the Brazilian Empire in the first place. Steam vessels were the only practicable means of communication. Thus in Brazil the overland journey from São Paulo to Mato Grosso took two and a half months by fast mule; by steamship, although the detour south through the River Plate and up through the River Paraguay was vast, it could be done in little over a fortnight. Tension over this route had been one of the causes of the Paraguayan war. Ammunition or other stores shipped from Rio de Janeiro, Brazil to the naval arsenal at Isla del Cerrito, near the mouth of the river Paraguay, had to travel an extensive water route.
Vessels requiring to be repaired could not be sent down to Buenos Aires for lack of facilities, and Rio de Janeiro was too far. Isla del Cerrito ("island of the hillock") was and is a small island at the confluence of the Paraná and Paraguay rivers. There the navy established a machine shop employing 20 men; a boatyard manned by 50 carpenters, etc; a coal bunker; a gunpowder mill; a naval hospital; and even a church. Good naval timber required for repairs was harvested locally. Because the river was blocked at Humaitá, stores required further north had to go by oxcart convoys on a route flanking Humaitá to the east. Those convoys were the object of repeated Paraguayan ambushes.
=== 3. Inherent difficulty in effecting the naval passage of Humaitá === Although some foreign observers were critical of the Brazilian navy's lack of zeal and implied that it should have forced the passage long ago, those observers were not naval men. One who was, Commander Kennedy of the Royal Navy, wrote that there were real difficulties, which he identified as these:
The river approach to Humaitá – which included the heavily armed preliminary fortifications at Curupayty – was shallow, narrow, and uncharted. It lent itself to the release of "torpedoes" (improvised contact naval mines). It was too shallow for the heaviest ironclad vessels, except during the river's seasonal rise. The seasonal difference between high and low water could be as much as 3 fathoms (18 ft; 5.5 m). But if these vessels did proceed at high water, they might be grounded, or trapped (neither able to advance or retreat), when the waters fell again. Commander Kennedy's evaluation:
It is difficult to conceive a more formidable obstacle to an advancing squadron than this small portion of the river between Tres Bocas and Humaitá. Further, although ironclad vessels were not supposed to be sunk by river batteries of the type possessed by Paraguay, they could be badly damaged. Cannonballs sometimes did penetrate the hull by going through a porthole or gunport. When this happened the shot could fracture or ricochet around inside the casemate producing appalling carnage. And even though most shots did not get inside the hull their force could start the bolts of the iron plating, or produce combat wounds by splintering the wooden backing. For inexperienced seamen inside these vessels the effect could be terrifying. In any case it would have been necessary, somehow, to cut or evade the chain boom, or else be detained under the Paraguayan artillery indefinitely.
According to the English-language Buenos Ayres Standard Experienced American and English and French naval officers, who had seen Humaitá, inspected the position, and gone through the batteries, all unanimously agreed on its extreme strength.
4. Dissension amongst the commands
The capture of Humaitá was an early example in modern warfare of combined operations, requiring cooperation between land and naval forces but as will now be described there were serious problems. Argentina and Brazil were traditional enemies. The alliance between them was that of "dog and cat", only brought about when López declared war on them both; it was fraught with mistrust and veiled antagonism. For political reasons the Argentine General Bartolomé Mitre was nominally commander-in-chief, but this went down badly in Brazil whose land forces were much larger; in reality Mitre had to seek consensus with the Brazilian and Uruguayan commands. Further, the Treaty of the Triple Alliance had stipulated that the naval forces (to all intents and purposes the Brazilian navy, for the Argentine naval forces were small) were to be "under the immediate command" of the Brazilian admiral; and the Brazilian government made it plain that the navy was not taking orders from Mitre. During the war the Brazilian navy had been criticised for its inertia. It was the modern ironclad vessels of the Brazilian navy that had stood by and allowed the retiring Paraguayan army to escape across the River Paraná on rafts – together with 100,000 head of rustled cattle – without doing anything to stop them. Those same vessels had been defied by two Paraguayan chatas (flat-bottomed, towable barges mounting a single gun). Although the Brazilian naval command protested that the shallow river waters enjoined caution, the Brazilian soldiery and the Emperor Pedro II were disgusted. As a result, the Brazilian Admiral Tamandaré had been relieved of his command and Joaquim José Inácio (1808–1869) had taken over his functions on 2 December 1866. The naval command was thoroughly distrusted by General Mitre and the distrust was mutual, for the Brazilian commands, military and naval, suspected the Argentines would be only too pleased if the Brazilian navy was destroyed in the war, since it would weaken Brazilian power in the River Plate region. The more Mitre asked the navy to be bold, the more they suspected him. In practice Mitre never attempted to give direct orders to the Brazilian navy, instead seeking to persuade it through the senior Brazilian land commander.
=== 5. Ageing naval command === The new admiral Inácio had had a distinguished and brave fighting career in the days of the blue-water sailing navy. But he had not been to sea for years, pursuing a career as a bureaucrat and then a politician. In Paraguay Inácio became unwell, a prematurely old man, "a ghost of an admiral", as the modern Brazilian historian Francisco Doratioto put it.
According to Artur Silveira da Mota, commander of the ironclad Barroso (who was a full naval captain by the age of 26, and later in life given the rank of admiral and made Baron of Jaceguai) "most of the senior naval command showed themselves to be incompetent for war service, whether for advancing years or for being too long in sedentary jobs", an assertion with which Doratioto was inclined to agree.
== Difficulties facing Paraguay == Paraguay was fighting on her home territory; her artillerymen were good; she could cast large guns at her foundries at Asunción and Ibicuy; and foreign observers − including the Allies − were unanimous that her men were superbly brave fighters. However early in the war she had been cut off from the outside world by the Brazilian naval blockade and had to make do with the resources within the country.
=== No armoured vessels === In particular, she did not possess a single ironclad vessel. She had placed orders for ironclads at British and French shipyards, but López had attacked Brazil and Argentina without waiting for these to be delivered. Because of the blockade he stopped making payments. Brazil negotiated to purchase the work-in-progress and to have it completed; and hence took delivery of the ironclads Bahia, Colombo, Lima Barros, Cabral and Silvado, all of which were originally destined for Paraguay. According to Burton it was the general opinion that with just one ironclad Paraguay could have cleared the river.
=== Little armour-piercing weaponry === She also had little armour-piercing shot, and for the same reason. According to the diplomat Gregorio Benítes, who represented Paraguay abroad during the war:
If Marshal López had not been precipitate in accepting the war, to which he was provoked by the Empire of Brazil, and had he given himself time enough to take delivery of the great monitors and armaments which he had ordered in Europe, among the last some 36 coastal artillery pieces made on the Krupp system, contracted for in Germany with the personal intervention of the undersigned, then not a single fresh-water ironclad would have been able to attack the aforementioned fortresses with success, if they had been armed with that powerful artillery. In effect, whoever has any idea of the formidable power of Krupp artillery, will understand that such cannon being mounted in the batteries of Curuzú, Curupaity and Humaitá, the triple alliance would not have had one single ironclad which could venture under their fires, on pain of certain disaster. Furthermore, López left it too late to order these weapons; so that the Baron of Itajubá the Brazilian accredited diplomat in Berlin, on finding out about the acquisition of those cannon on behalf of Paraguay, made use of his right under international law to require the detention of the said artillery.
== Allied initiative == On 5 August 1867 Mitre presented a plan to his nominal subordinate the commander of the Brazilian land forces the Marquis of Caxias. Its preferred feature was the capture of Humaitá by cutting off its lines of communication: the land forces would flank the fortress to the east and the naval forces would interdict river communications. For this to be done, the Brazilian naval forces had to force the river passage. Caxias agreed, and ordered the Brazilian admiral Joaquim José Inácio to proceed. But the latter was not at all keen: Humaitá was a very strong point and, if the Brazilian squadron did get past it, how would it communicate with its forward base presently at Curuzú? It would be trapped. Caxias was impressed by Inácio's reasoning and told Mitre so. Mitre was for once insistent, and there followed a correspondence in which, eventually, the Brazilian admiral agreed to attack the preliminary outwork of Curupayty – a few miles down the river – and, if he got past there, to assail Humaitá at a later date.
Passage of Curupayty
Curupayty was an outwork a few miles downriver from the fortress of Humaitá, and part of the Humaitá defensive complex. It lay at the corner of the Quadrilateral – the line of earthworks that protected Humaitá from seizure on its landward side – at the site where the disastrous land battle had taken place. Its river artillery alone comprised 35 heavy guns; indeed the Paraguayans had partly denuded Humaitá of guns to reinforce Curupayty. The largest gun threw a spherical 10-inch (25 cm) shot; it was called the Cristiano (because it was made by melting down bells contributed by all the churches of Paraguay).
=== The Brazilian ironclads dash past the lower fort === On 15 August 1867 at 0640 hours the Brazilian ironclads went into action. They were:
In the table the symbol P denotes that the vessel had originally been ordered by Paraguay, but obtained by Brazil in the circumstances already explained. The Brazilian admiral Joaquim Inácio was in overall command from the bridge of Brasil. Lashed to the port side of Brasil was the steam messenger Lindoya (to assist her in turning); Colombo and Cabral each towed a chata (flat-bottomed barge). At this point the river had two channels. One was deeper, but it ran closer to ("within pistol shot of"") the enemy batteries, and the current was stronger. In the other, or shallow, channel the risk of running aground was far greater; furthermore, a Paraguayan deserter claimed torpedoes had been placed there recently. Inácio chose to proceed by the channel closer to the batteries, and his choice was vindicated. While wooden vessels of the Brazilian navy provided covering fire the ironclads dashed past Curupaty. It took each vessel about 40 minutes to get past. Even so, some vessels were badly damaged. A shot penetrated Tamandaré through a gunport killing or wounding 14 of her crew. Her engine was damaged and stopped leaving her adrift under the guns of the fort; she was rescued by Silvado who threw her a cable and took her in tow. Tamandaré's commander Elisário Barbosa lost his left arm. According to Commander Kennedy RN the accident to Tamandaré obliged Colombo, which was following astern, to stop her engines in order to avoid fouling her. The strong current brought her broadside on, making her unmanageable. She drifted close to the Paraguayan guns, which did some very serious damage before she could be backed out of her dangerous position. There were 25 Brazilian casualties including three killed. The ironclads, by taking the channel nearest to the Paraguayan guns, had escaped a more serious danger, for a number of torpedoes were afterwards found laid down in the other channel. For this feat on 27 September Joaquim Inácio was awarded the noble title of Barão de Inhaúma (Baron of Inhaúma). According to Paraguay's then chief engineer George Thompson, López gave it out that he had allowed the fleet to pass Curupayty on purpose, to trap it and starve it out, and that it would soon have to repass Curupayty, where he would sink it. This is corroborated by Juan Crisóstomo Centurión, a Paraguayan journalist working for the López regime at the time. The government newspaper El Semanario de Avisos y Conocimientors Útiles claimed a victory, writing: "The [Brazilian squadron is wounded in the heart, and we have one part of its ironclads prisoner between Curupaty and Humaitá, devoid of resources, without means of repair, and given over to the fury of our cannon; the rest will have to come to its aid, and follow the same road of shame and defeat". And "The ironclads must now make every effort to patch themselves up; but the impacts made by the solid shot of Curupayty cannot be repaired, except in arsenals, and none of those can be found between Curupaty and Humaità.
== The chain boom of Humaitá deters Inácio == Inácio sent Barroso upriver to reconnoitre Humaitá; she reported that the river was indeed blocked by a boom of three parallel chains floating on pontoons. The tactical problem now was how to get past the chain boom.
There was some military know-how about this. According to a professional paper published some years before by the Corps of Royal Engineers in Dublin a heavy steamship could snap almost any chain provided it was moving fast enough; for this reason it was prudent for the defenders to provide three chains − breaking the first reduced the ship's velocity. The paper said that a 1,000 ton ship steaming at 15 knots could snap a chain of 2.5-inch round iron links. The chain link diameter at Humaitá was not known to the attackers; the largest ironclad (Brasil) was 1,500 tons but her top speed was only 11.3 knots; she would be steaming against an adverse current of up to 3 knots; and not one, but three chains were reported. In his memoirs the Brazilian minister of marine wrote they knew that their ships would have to proceed single file in the narrow channel: if the first failed to snap the chain it could neither back up nor turn round, nor get up enough way for a second, successful attempt at the chain. The vessels would be trapped under the guns of Humaitá. Further, the Brazilians feared that the Paraguayans, who were desperate to get their hands on an ironclad, might try to seize the isolated vessel by human wave boarding tactics (which, indeed, the Paraguayans tried to do more than once on later occasions). The snapping method was not tried.
There were alternative, if heroic, methods of severing a chain boom. Sending out a party under the defending guns to cut it with a cold chisel was one. Seizing the chain house or blowing it up with gunpowder were others. Both methods were urged upon the Brazilians by General Mitre but were not attempted. The river was falling. From the main article on Inácio it appears that he was prone to depression; on 30 August he sent his subordinate commanders a questionnaire as to the feasibility of passing Humaitá; the questions suggested the answers he wished to receive; for example:
Finally: in the present revolutionary circumstances of the Republics of the River Plate [meaning Argentina], knowing their feelings about the Empire of Brazil, is it prudent to risk the most important part of our Navy to a certain and inevitable ruin, without being convinced that it avoids a greater evil, or gives success to our cause and triumph to our arms? His subordinates responded appropriately. Inácio informed Caxias: "I shall not risk the fleet". On 26 August Caxias told Mitre that, shortly, the fleet would need to retire again below Curupayty; in those circumstances it would be "unpardonable recklessness" to attempt to pass Humaitá; accordingly, he intended to order it to retire to its original position. There followed a correspondence between Mitre and Caxias in which the nominal commander-in-chief and his nominal subordinate argued the toss in the diplomatic language of the era; Mitre reminded him of the divers occasions when (he claimed) the navy had let them down. To descend below Curupayty again would look weak, as well as exposing the ironclads to battery fire, torpedoes and the risk of seizure by boarding. The ironclads stayed above Curupayty. According to George Thompson, if the ironclads had attempted to pass Humaitá at that point they would have faced only three 8-inch guns and about six 32-pounders; the other guns had been taken to reinforce Curupayty.
The Brazilian ironclads are trapped between the forts of Curupayty and Humaitá
The vessels were in enemy waters between two fires: Curupaty and Humaitá. The river fell, and would not reach maximum until sometime in 1868. It now became necessary to extend the Brazilian navy's lines of communication – already long by the standards of the day – even further.
=== The Brazilian navy establishes a regular steamship line to supply its warships in the River Paraguay === On 4 October 1867 the navy minister Afonso Celso de Assis Figueiredo by order established a liner service from Rio de Janeiro, Brazil exclusively to supply the Brazilian navy in Paraguay. Using four steamships, it had scheduled sailings, each way, on the 15th and 30th of every month. From Rio steamers stopped to coal at Montevideo, Uruguay and then steamed non-stop to Corrientes, Argentina to drop off correspondence before proceeding to the naval arsenal of Cerrito near the mouth of the River Paraguay. According to Afonso Celso's memoirs whatever the Brazilian vice-admiral asked for was promptly supplied from Rio.
=== The Brazilian navy builds an emergency military railway through the Chaco to its trapped ironclads === However, since the ironclads were cut off above the fort of Curupayty, the Brazilian government at once ordered the navy to build a supply line through the Chaco. The Chaco is the territory to the west of the River Paraguay. In those days it was claimed by both Argentina and Paraguay, but was uninhabited, except by a few nomads. In this coastal region it was almost impassable swamp. The supply line, named Affonso Celso after the minister of marine, ran between two improvised harbours on the west bank of the river, i.e. inland through the Chaco. They were dubbed "porto Palmar" (where the wooden vessels moored, below Curupayty) and "porto Elisário" (above); both were out of range of the Paraguayan guns. The ironclads moored at porto Elisário. It was possible to travel some of the way by a navigable creek called Riacho Quîá. From there the Brazilian navy at great effort built a military railway or tramway. At first drawn by animal power, later by an improvised steam engine, the line carried artillery guns, steam launches and heavy ammunition, as well as coal and other supplies. It was reported that the line conveyed 65 tons of supplies a day, its sleepers almost floating on the boggy ground.
The ironclads shell Humaitá
For five months the ironclads stayed in this precarious (and, from a sanitary point of view, deplorable) position, frequently going out to shell Humaitá, but not doing much damage. The only installation they could clearly see to hit was the church of San Carlos Borromeo, and they fired at it. Wrote Burton: "The Brazilians banged at the fane persistently as an Anglo-Indian gunner at a flagstaff; and the Paraguayans at times amused themselves with repairing it." Another source says that church was respected at first, but then shelled on purpose because Caxias claimed it was being used as a powder magazine and a watchtower. Its ruins still stand today, a tourist attraction, practically the only part of the fortress of Humaitá that survives. According to Artur Silveira da Mota, Admiral Inácio sank into inertia, rarely leaving his cabin aboard Brasil, instead writing picturesque articles for the weekly Semana Illustrada under the pen name Leva-Arriba (Get Up and Go), "a pseudonym which circumstances did not permit him to confirm by deeds".
