On 21 April 1820, the watch-tower at Capiro in Trujillo Port announced the approach of a Colombian flotilla. The port's garrison, commanded by Jose M. Palomar, at once made emergency preparations for the impending attack. At two o'clock in the afternoon the approaching flotilla hoisted a flag with two blue bars and a white one between them showing an escutcheon in the center similar to the Argentinian flag; Aury dispatched a boat to shore to demand the port's surrender within one hour. The town did not comply. The following day Commodore Aury moved the flotilla to the mouth of the Guaimoreto River and began bombardment. The attack started at 9 AM and lasted until 2 PM. The firing ceased when the flotilla was ordered out to sea and out of the reach of the port's cannons. A portion of the land force then attempted to enter the town by the rear, but was detected and driven out.