Great Britain, aroused by the tales of mistreatment of her merchant seamen (notably Robert Jenkins) and other hostile acts (provoked by British abuses of the Assiento and activities of her logwooders of the Honduran coast as well as by the unsettled Florida Border), declared war on Spain (19 Oct. 1739). His western flank protected by the friendly Creeks, Cherokee, and Chickasaw, Oglethorpe invaded Florida, captured forts San Francisco de Pupo and Picolata on the San Juan River (Jan. 1740), and besieged St. Augustine (May - July), breaking off when his rear was threatened. A spanish counterattack was crushed at the Battle of Bloody Swamp on St. Simon's Island (1742).

The War of Jenkins' Ear (1739-1742), which began in Europe on Oct. 19, 1739, and a year later merged into the War of Austrian Succession, had its repercussions in the southern colonies. England went to war with Spain over the mistreatment of English seamen whom the Spaniards accused of smuggling. The war took its name from Robert Jenkins, captain of the ship Rebecca, who claimed Spanish coast guards had cut off his ear in 1731. He exhibited the ear in the House of Commons and so arroused public opinion that the government of the British Prime Minister Robert Walpole reluctantly declared war on Oct. 23, 1739. Basically, the war was one of commercialrivalry between England and Spain. By the Treaty of Utecht (1713), which ended Queen Anne's war, Britain was allowed to participate in slave traffic with the Spanish colonies. A special Spanish fleet, however, interfered with this activity and the Spanish also objected to the English logwooders operating on the coast of Honduras. The other cause of the war was the continued dispute over the boundary of Spanish Florida in relation to Georgia. As soon as war was declared, Gov. James Edward Oglethorpe called on the citizens of Georgia and South Carolina to join in an invasion of Florida. The Spanish retaliated by attempting to invade those colonies by sea.

The War of Jenkins' Ear (1739-1742) continued with an invasion of Florida led by Gov. Oglethope of Georgia. He was protected on the west from the French by friendly Indians. He captured forts San Francisco de Pupo and Picolata on the San Juan River. From May to July he besieged St. Augustine, but broke off the attack when his rear guard was threatened by the Spanish.

In the Battle of Bloody Marsh on St. Simons Island, one of the Sea Islands off the southeast coast of Georgia, the Spanish attacked Fort Frederica, which had been constructed by Gov. Oglethorpe in 1736 to protect the colony. The Spanish were repulsed in a bloody battle that was a decisive engagement of the War of jenkins' Ear.