Tuyuti May 24, 1866 Strategic Context With Brazil and Uruguay at war, Paraguayan President Francisco Solano López invades southern Brazil in support of Uruguay in López perceives war with Brazil as inevitable and hopes to fight a short war to achieve favourable terms before Paraguay’s strategic situation worsens. Brazil initially ignores the Paraguayan attack and focuses on ensuring a new Uruguayan government. In 1865, López invades Argentina, provoking Argentina, Brazil and Uruguay to form a triple alliance to defeat Paraguay. The war goes badly for Paraguay in 1865 the Allied blockade diminishes its resources, unsuccessful offensives sap manpower and its navy is destroyed at the Battle of Riachuelo. An Allied army comprising all three nations 45,000 strong invades Paraguay in early López miraculously raises his strength to 30,000 but his soldiers are ill-equipped and officers inexperienced. López hears that the Allies plan to attack on May 25 and decides on an all-out attack to decisively defeat the Allies before they can advance. Despite the risk of such an attack, López reasons that time is not on Paraguay’s side in this war and that a decisive battle must be won. Inexplicably however, he remains to the rear with 6,000 troops in reserve. Stakes + An Allied victory would worsen Paraguay’s manpower shortages and permit an advance deeper into Paraguay. + A Paraguayan victory would push the Allied army into a swamp, forcing it to the brink of destruction and straining the triple alliance. By Jonathan Webb, 2011 ©

Tuyuti, 1866 Strength  Allies  Well  Paraguayans  Well  24,000  Francisco Selano López  35,000  Manuel Luís Osório By Jonathan Webb, 2011 ©  Bartolomé Mitre

Allies (Osório/Mitre) Resquin Osório Mitre Marco Barrios Diaz Barrios López deploys his army in four assault columns, concealing them in the thick brush. He plans to use the dense brush to advance the columns forward before attacking simultaneously at dawn. The two center columns under Diaz and Marco are to pin the Allied front while the two outside columns under Barrios and Resquin thrust deep into the Allied rear, thus unhinging the entire Allied position. The Allied army comprises the Brazilians under Osório on the left and the Argentineans under Mitre on the right; the small Uruguayan contingent under Flores forms a vanguard near the mixed, well-protected artillery at the center. The Paraguayan assault columns advance much more slowly than expected, often moving single file through thorny brush. The result is that the attack cannot begin until noon and even then develops haphazardly, not concurrently as planned. Diaz’ force attacks first: its cavalry runs over the Allied pickets before charging the Allied artillery and being repulsed. Marco’s force joins the attack but cannot even come close to the Allied artillery and thus veers to the right to avoid the Allied firepower. They support Diaz whose infantry make easy targets for Brazilian rifles as they cross deep marshland. The Brazilian divisional commanders react quickly: Monteiro forms up his forces on either side of the Allied artillery and Sempaio leads his forces forward to meet the Paraguayan attack. On the flanks, the other Paraguayan columns are poised to enter the battle. Marco and Diaz repeatedly charge the Brazilian lines against which the Paraguayans suffer disproportionately but continue nonetheless. On the Allied left, Paraguayan forces suddenly burst from the brush, routing the cavalry stationed there; they are only initially contained by Brazilian volunteers in the sector. Much of Barrios’ force veers to the left to support the Paraguayan attack at the center rather than bunch up behind the advance columns. Osório reacts by sending Argolo’s division to secure his left flank. On the Allied right, rather than maneuver around the Argentinean forces to hit the Allied rear, Resquin launches a frontal assault against Argentinean firepower. Paraguayan cavalry almost completely surround the lead Argentinean division. The slaughter in the center continues but does not discourage the Paraguayans from attacking relentlessly. On the Allied left, more Paraguayan infantry emerge from the brush only to be cut down by Brazilian fire. Osório reinforces this sector for good by sending Sousa Neto’s division. On the Allied right, Mitre must shift units to meet the growing Paraguayan attack. A few units of Paraguayan cavalry manage to get through to the Allied rear but they are promptly destroyed. The Paraguayan ranks are thinning, the attack losing traction while Osório and Mitre feel their lines are secure enough to hold back sizeable reserves. Unit by unit, the Paraguayan attack simply disintegrates. Excessive battlefield smoke prevents each side from realizing just how many casualties the Paraguayans have suffered. A complete lack of Allied cavalry prevents further devastation of the Paraguayan army. Paraguayans (López) Allies (Manuel Luís Osório/Bartolomé Mitre) 35,000 Paraguayans (Francisco Selano López) 24,000

Tuyuti, 1866 Casualties & Aftermath Allies: Paraguayans: 4,000 or 11% 13,000 Or 54% By Jonathan Webb, 2011 © The Allied victory could not be immediately exploited and attempts to do so were rebuffed at the Battles of Sauce at Curupaity in July and September respectively. López quickly replenished the ranks of his army but with boys and old men. The war dragged on until March 1870 when Brazilian soldiers captured and killed López. The Allies imposed strict terms on the ravaged Paraguayan nation which ceded a quarter of its territory. The war shifted the regional power balance abruptly, pushing Brazil and Argentina into conflict.

The Art of Battle: Animated Battle Maps By Jonathan Webb, 2011 ©