Union General Nathaniel Banks’ strategy in late 1863 involved invading South Texas and then slowly moving northward along the Texas coastline, seizing Confederate ports and installations.
Once Banks’ forces captured Brazos de Santiago at the mouth of the Rio Grande River in early November his troops moved quickly to the north, capturing Corpus Christi on November 16 and overwhelming a Confederate battery protecting Aransas Pass the following day. By Sunday, November 22, 1863 Banks’ forces began an assault against Fort Esperanza, the main Confederate fortification on Matagorda Island.
By the end of the month Banks would control the fort, the island, and nearby area. Except for Galveston and the Sabine Pass area, the entirety of the Texas coast would be controlled by Union forces, if Banks’ troops could not be expelled.