Battery E participated in the expedition to the Rio Grande from 27 October to 2 December 1863. On 6 November, the 13th Maine and 94th Illinois Infantry Regiments plus a Missouri battery occupied Brownsville. A total of 6,998 Union troops took part in the effort. The expedition's goals were to raise the U.S. flag in Texas, to cut off the cotton trade with Mexico, to damage the Texas economy, and to serve warning to the French occupation force in Mexico. On 16 November, 1,100 Federal troops seized Mustang Island and captured 98 Confederate soldiers and three heavy cannons. Soon after, the Union forces marched north on San José Island and crossed to Matagorda Island. At the Battle of Fort Esperanza, a battery of 1st Missouri Light Artillery bombarded the fort, which guarded the Pass Cavallo inlet. The fort was abandoned by the Confederate garrison on 29–30 November. Battery E performed garrison duty at Ducrow's Point and Brownsville before being mustered out in June 1864.