Pensacola’s defense in early 1781, consisted of Fort George, a fort topped by palisade. North of Fort George, Campbell built the prince of Wales Redoubt, northwest was the Queens Redoubt both built in 1780. Near the mouth of the bay, Campbell erected a battery called Fort Barrancas Colorada, by mid October 1780, Spain had finalized all preparations for the first invasion of Pensacola. A powerful fleet of 11 warships and 51 transport ships set sail on October 16,1780. Two days later, a gulf hurricane devasted the fleet at sea, scattering the ships throughout the Caribbean, Campeche coastline, and the Mississippi River. The survivors of the squadron limped back to Havana on November 17 and the damage to the fleet was an appalling setback
The following February Galvez, under the command of Captain Jose Calvo de Irizabal , embarked his flag with the Spanish fleet. With about 1,300 men, the regular troops including Arturo O’Neil-future governor of east and west Florida- commanding 319 men. Some of which included militias of biracial and free afro-Cubans. Galvez also had ordered troops from New Orleans and Mobile to assist. The Spanish expeditionary force sailed from Havana on February 13 and arrived outside Pensacola Bay on March 9.
Sailing the Spanish ships into the bay turned to be difficult, as it had been in the previous years capture of Mobile. Galvez boarded the Galveztown and on March 18 he sailed through the channel and into the bay, with three Louisiana ships following. The very next day they did the crossing and Calvo sailed back to Havana. March 24 the Spanish army and militias moved to the center of operations. O’Neill’s patrol scouts landed on the mainland and blunted an attack by 400 Indians allied to the British, these soon joined forces with the Spanish troops arriving from Mobile.
During the first weeks of April, the troops established encampments and began the extensive preparations for the siege. On April 12, Galvez was wounded by gunfire viewing the British fortifications, so the battlefield was formally given to Col. Jose de Ezpeleta, a close friend of Galvez. April 30, Spanish batteries opened fire beginning the full-scale attack on Pensacola’s fortifications. With the Spanish’s navy fear that the sea would crash the wooden ships on the shore, they were forced to withdraw. The army was on its own, May 5, Galvez made arrangements with Tallapoosa Creeks to cease, or suspend their attacks and agreed to purchase beef cattle from them in exchange. May 8, a howitzer blast hit the magazine in Fort Crescent, killing 57 British troops and devasting the fortification. Ezpeleta led a light infantry and was able to take charge of Fort Crescent and move the canons in place to open fire onto the next two fortifications. The British fired back but were overwhelmed with Spanish firepower.Facing the 7,400 infantry and 10,000 sailors and marines, were the 1,300 British regulars, militia, loyalists and natives of the area, and their 500 indian allies. From March 29 to April 30, the Spanish force dug out siege lines and batteries under artillery fire and constant attacks by the British, especially from the Indian allies. During this time Galvez was wounded. On April 30, the Spanish unleashed a heavy barrage of cannon fire to signal their attacks to begin. From April 30 to May 10, Fort George and nearby Fort Crescent, a smaller fortification, were pummeled and began to slowly give way to Spanish pressure. More good news for the Spanish came when a tribe of local Tallapoosa Creeks bearing meat for the military.