Bernardo de Gálvez, the energetic governor of Spanish Louisiana, had immediately begun offensive operations when Spain entered the American Revolutionary War in 1779.

In September 1779 he had gained complete control over the lower Mississippi River by capturing Fort Bute, then shortly thereafter obtaining the surrender of the remaining British forces on the river following the Battle of Baton Rouge.

Following these successes, he began planning operations against Mobile and Pensacola, the remaining British presence in the province of West Florida.

Gálvez has assembled a mixed force of Spanish regulars and militia in New Orleans.

He had requested additional troops from Havana for operations against Mobile and Pensacola in 1779, but his requests had been rejected.

Before departing New Orleans, he dispatches one of his lieutenants to Havana to make one last request.

A fleet of twelve ships carrying seven hundred and fifty-four men had set sail on January 11, 1780, reaching the mouth of the Mississippi on January 18.

They are joined on January 20 by the Gálveztown (brig sloop), under the command of Captain William Pickles and with a crew of fifty-eight.

A storm had scattered the fleet on February 6, but all ships had arrived outside Mobile Bay by February 9.

The fleet had encountered significant problems actually getting into the bay.

Several ships had run aground on sand bars, and at least one, the Volante, had been wrecked as a result.

Gálvez had salvaged guns from the wreck and set them up on Mobile Point to guard the bay entrance.

On February 20, reinforcements had arrived from Havana, bringing the force to about twelve hundred men.

By February 25, the Spanish had landed their army on the shores of the Dog River, about ten miles (sixteen kilometers) from Fort Charlotte.

They are informed by a deserter that the fort is garrisoned by three hundred men.