Why William Brown's fleet was seized

British and French ships anchor beside William Brown's Argentine vessels before he requests permission to return to Buenos Aires. Permission comes with a demand to surrender the British and French sailors serving in his fleet. Brown asks to release them in Buenos Aires because his crews are overwhelmingly Irish, then sails without receiving an answer. British and French forces board and seize his ships after that departure. Argentine officers return to Buenos Aires, while Brown and the foreign sailors are forbidden to serve under the Argentine flag for the rest of the conflict.