in the autumn of 1863, lincoln and chief of staff henry halleck informed banks that plans should be made for operations against the coast of texas, chiefly for the purpose of preventing the french in mexico from aiding the confederates or occupying texas, and to interdict confederate supplies from texas heading east. the second objective he attempted to achieve at first by sending a force against galveston; his troops were badly beaten in the second battle of sabine pass on september 8. an expedition sent to brownsville secured possession of the region near the mouth of the rio grande and the texas outer islands in november.