| Part of the Paraguayan War | |
 Lithography depicting war prisoners and Paraguayan families captured and tortured in San Fernando | |
| Date | 21 December 1868 |
|---|---|
| Location | San Fernando, Paraguay |
| Participants | Francisco Solano López |
The San Fernando massacre (Spanish: Matanza de San Fernando) was an episode that took place on 21 December 1868, on the eve of the Battle of Lomas Valentinas, during the Pikysyry Campaign in the Paraguayan War, which consisted of the summary trial and execution of hundreds of prisoners by order of Paraguayan president Francisco Solano López. Some prisoners were accused of plotting an alleged conspiracy to overthrow López. Among the dead was López's own brother, Benigno López.