| Conflict: | Pikysyry maneuver |
| Partof: | the Paraguayan War |
| Date: | 21 December 1868 |
| Place: | Formosa province, Argentina |
| Result: | Allied victory |
| Combatant1: |  Paraguay |
| Combatant2: | |
| Commander1: | |
| Commander2: | |
| Strength1: | 2,000 men[1] |
| Strength2: | 8,000 men |
| Casualties1: | 600 killed, 200 captured |
The Pikysyry maneuver was a tactic used by Brazilian marshal Luís Alves de Lima e Silva, Duke of Caxias, during the Paraguayan War to outflank the Paraguayan southern defense line along the stream of Pikysyry consisting of 142 gun platforms along a line 9.1 km long, built by the British engineer Lt. Col. George Thompson. Just to the north were the batteries of Angostura, protecting the River Paraguay. Marshal Caxias decided to attack from the Paraguayan rear by constructing a 10.7 km road on the Chaco side of the river starting at Santa Theresa.[1]
On 11 Oct. 1868, 1,122 men under the command of Lt. Col. Antonio Tiburcio landed near Santa Theresa on the west side of the Paraguay River. An additional 2,925 infantry, 327 pontoniers, 198 artillerymen and 94 cavalry were landed and overall command for building the road was the responsibility of Lt. Col. Rufino Galvao of the Engineers. The road was constructed of palm tree trunks. On 27 Nov. Marshal Caxias moved his headquarters to the Chaco side of the river. By early December, the road had been completed to Santa Helena and 19,000 Allied troops were ready to cross over to San Antonio.[1]
After the successful battles of Ytororó and Avay, the allied army was ready to capture the Paraguayan defenses at Pikysyry. A column of 2,700 men under general João Manuel Mena Barreto mounted a flanking movement while troops under general Juan Andrés Gelly y Obes made a simultaneous feint to the front. The December 21 attack was a complete surprise to the Paraguayans.[1]
Some 500 Paraguayans escaped to Angostura and another 200 to Lomas Valentinas.[1]
Argentina
Uruguay