In mid-May 1846, war broke out between the United States and Mexico. "Truxtun" was recommissioned at Norfolk on 8 June under the command of Lt. Edward Weston Carpender. On the 15th, she passed El Morro castle and anchored in Havana harbor, Cuba. For the next six weeks, the brig operated off the coast of Cuba. On 2 August, the warship cleared Havana and, on the 9th, joined the blockading American fleet just off the Mexican coast at Sacrificios Island. On the 12th, Lt. Carpender received orders instructing him to relieve sloop of war "John Adams" on station off Tampico. Early in the evening on 14 August, the brig was heading north in a gale about 100 miles from her destination. She turned in towards land in order to be able to provision ashore the following morning. That maneuver brought her dangerously close to Tuxpan Reef, and she soon ran hard aground. The gale continued to blow and drove her harder upon the reef. Still, her officers and crew tried to free her and declined a Mexican offer to surrender. On the morning of the 15th, she dispatched one of her cutters to the anchorage at Anton Lizardo to seek help.