On May 25, 1865, in Mobile, Alabama, in the Southern United States, an ordnance depot or "magazine" exploded, killing some 300 persons. This event occurred just after the end of the American Civil War, during the occupation of the city by victorious Federal troops.

The depot was a warehouse on Beauregard Street, where the troops had stacked some 200 tons of shells and powder. Some time in the afternoon of May 25, a cloud of black smoke rose into the air and the ground began to rumble. Flames shot up into the sky and bursting shells were heard throughout the city. In the nearby Mobile River, two ships sank, and a man standing on a wharf was blown into the river. Several houses collapsed from the concussion.

A reporter for The Mobile Morning News newspaper described "bursting shells, flying timbers, bales of cotton, horses, men, women, and children co-mingled and mangled into one immense mass". He continued: "The heart stood still, and the stoutest cheek paled as this rain of death fell from the sky and crash after crash foretold a more fearful fate yet impending ... old and young, soldier and citizen vied with each other in deeds of daring to rescue the crumbled and imprisoned."On the heels of the explosion came fires, which burned until the entire northern part of Mobile lay in smoking ruins. A huge hole where the warehouse once stood remained for many years, a reminder of the disaster.

The exact cause of the magazine explosion was never determined. Some northern newspapers tried to pin the blame on an imagined gang of unreconstructed Confederate officers. Most people, though, accepted that it was the result of simple carelessness on the part of workers handling wheelbarrows full of live ammunition.

Mobile ( moh-BEEL, French: [mɔbil] (listen)) is the county seat of Mobile County, Alabama, United States. The population within the city limits was 195,111 as of the 2010 United States Census, making it the third-most-populous city in Alabama, and the most populous in Mobile County.

Alabama's only saltwater port, Mobile is located on the Mobile River at the head of the Mobile Bay and the north-central Gulf Coast. The Port of Mobile has always played a key role in the economic health of the city, beginning with the settlement as an important trading center between the French colonists and Native Americans, down to its current role as the 12th-largest port in the United States.Mobile is the principal municipality of the Mobile metropolitan area. This region of 412,992 residents is composed solely of Mobile County; it is the third-largest metropolitan statistical area in the state. Mobile is the largest city in the Mobile–Daphne−Fairhope CSA, with a total population of 604,726, the second largest in the state. As of 2011, the population within a 60-mile (100 km) radius of Mobile is 1,262,907.Mobile was founded in 1702 by the French as the first capital of Louisiana. During its first 100 years, Mobile was a colony of France, then Britain, and lastly Spain. Mobile became a part of the United States in 1813, with the annexation by President James Madison of West Florida from Spain. The city surrendered to Federal forces on April 12, 1865, after Union victories at two forts protecting the city. This, along with the news of Johnston's surrender negotiations with Sherman, led Taylor to seek a meeting with his Union counterpart, Maj. Gen. Edward R. S. Canby. The two generals met several miles north of Mobile on May 2. After agreeing to a 48-hour truce, the generals enjoyed an al fresco luncheon of food, drink, and lively music. Canby offered Taylor the same terms agreed upon between Lee and Grant. Taylor accepted the terms and surrendered his command on May 4 at Citronelle, Alabama.Considered one of the Gulf Coast's cultural centers, Mobile has several art museums, a symphony orchestra, professional opera, professional ballet company, and a large concentration of historic architecture. Mobile is known for having the oldest organized Carnival or Mardi Gras celebrations in the United States. Its French Catholic colonial settlers celebrated this festival from the first decade of the 18th century. Beginning in 1830, Mobile was host to the first formally organized Carnival mystic society to celebrate with a parade in the United States. (In New Orleans, such a group is called a krewe.)