Second Battle of Nanawa The Second Battle of Nanawa was a battle fought from July 4−9 , 1933 , between the Bolivian and Paraguayan armies during the Chaco War . It was one of the bloodiest battles fought in South America in the 20th century , coming to be labeled as the " South American Verdun " by comparison with the Battle of Verdun of World War I . Background . The battle was the last Bolivian attempt to capture the heavily fortified stronghold of Nanawa , a salient in the southern front . By capturing Nanawa the Bolivian army hoped to isolate Isla Poí , the Paraguayan headquarters to the northeast , and ultimately reach the city of Concepción , on the Paraguay River . Nanawa ( Enxet for " carob tree forest " ) had been founded as a small outpost in 1928 by Ivan Belaieff , a white Russian officer who joined the Paraguayan army in the 1920s . In December 1932 the Bolivian army took over a number of Paraguayan outposts between Nanawa and the Pilcomayo River . Realising that a major offensive was looming , the fort ' s commander , Col . Luis Irrazábal , built up a horsehoe - shaped defense facing west around the old outpost and gathered under his command four regiments and several minor units that made up the Paraguayan Fifth Division . On January 20 , 1933 , Nanawa was the subject of a massive Bolivian assault , which stalled after several days of heavy fighting and was eventually beaten back by the Paraguayan garrison . The Bolivian army suffered 2 , 000 casualties . By March , Nanawa became the headquarters of the Paraguayan III Army Corps . The battle . The battle began on July 4 at 9 : 00 a . m . with the explosion of a large mine just 30 yards short of the main Paraguayan redoubt , followed by a massive frontal attack . Part of the redoubt was seized by the attackers . The Bolivian army engaged the defenders with artillery and mortar fire , air strikes , three Vickers light tanks , two Carden - Lloyd tankette s and four flamethrower s . The attackers staged a two - pronged assault , one from the north and the other from the south , while a diversionary force established a blocking position in the center . The Paraguayan troops responded with their own artillery fire and 7 . 62mm armor - piercing rounds . They eventually recovered the fortifications that had been overrun by the Bolivians . The Bolivians lost one tank to artillery fire , while one of the tankettes was damaged by small - arms fire and the other became stuck in a ditch . Both of them were withdrawn from the front line after this battle , while the crippled tank was eventually blown up by Paraguayan sappers . Four Potez 25 s fighter - bombers being used as transport aircraft resupplied the exhausted Paraguayan stockpiles by delivering hand grenades and ammunition . The planes were stripped of their rear machine guns in order to use the gunner ' s cockpit to load 115 kg of ammunition . The aircraft departed from Isla Poí to the south flying over hostile territory and landed on an improvised airstrip close to the battle lines . The airstrip had been hastily built during the first Bolivian offensive . The pilots handed over 1 , 650 kg of ammunition to the stronghold on the first day of operation . Three Potezes were hit by ground fire and forced to make hard landings , but all were eventually recovered and rebuilt . Aftermath . Once the attack was repelled the Paraguayans , on July 11 , launched an unsuccessful counterattack on enemy positions outside the complex , in a wooden area southwest of the Paraguayan outpost of Gondra . The second battle of Nanawa was a major turning point in the war , since the Paraguayan army regained the strategic initiative that had belonged to the Bolivians since early 1933 .