San Jacinto didn’t end the fighting between Texas and Mexico. There were some skirmishes after April 1836.
In March 1842, Mexican troops briefly invaded parts of the Republic (although quickly withdrew). But they returned in September and captured San Antonio. A fight ensued at Salado Creek; the Texans won an overwhelming victory and drove the invaders back to Mexico.
But not before a tragedy. Ffity-three men led by Nicholas Dawson were captured by Mexican cavalry, which proceeded to gun down 36 of the Texans.