Final answer:
The USS Chesapeake, an American warship, was attacked by the British HMS Leopard in 1807 after refusing a demand to search for deserters, escalating tensions that contributed to the War of 1812.
Step-by-step explanation:
The American warship that was attacked in 1807 by the British was the frigate USS Chesapeake. The incident occurred when the HMS Leopard, a British warship, demanded to search the Chesapeake for deserters. The captain of the Chesapeake, James Barron, refused to comply, and the Leopard then opened fire, leading to American casualties and the seizure of four sailors. This event significantly escalated tensions between the United States and Great Britain, contributing to the outbreak of the War of 1812. It illustrated the British practice of impressment and the open season on American ships, which played a significant role in the maritime conflicts of the era.