Siege of Humaitá

The siege of Humaitá was a military operation in which the Triple Alliance (Brazil, Argentina and Uruguay) flanked, besieged and captured the Fortress of Humaitá, a Paraguayan stronghold that was referred to as the Gibraltar of South America. It fell on 26 July 1868. It can be considered the key event of the Paraguayan War since the fortress had frustrated the allied advance into Paraguay for more than two years. However it did not surrender as the defenders escaped, most of them to fight another day.

The allies were severely criticised for the time it took them to take the installation, whose strength was belittled. But they were essentially a pre-professional army fighting a long way from home against an unaccustomed defence tactic: artillery in prepared, entrenched positions firing a hail of anti-personnel shot. Further, they were battling in unprecedented terrain — most of it impassible, all of it unmapped — in the wetlands of southern Paraguay. It gave the Paraguayans, who fought with exemplary courage despite being abysmally supplied, a huge advantage.

Moreover the allies, who at first had attempted to take the fortress by frontal attack from the Paraguay River, had instead suffered a catastrophic defeat; this had disorganised and demoralised their forces. Restoring their military effectiveness was a task that fell on the shoulders of the new commanding general the Marquess of Caxias. For political reasons he could not risk another disaster.