Based on the restrictions of the London Naval Treaty, American designers conceptualized a gunboat to solve a wide range of tasks—from providing fire support to the Marine Corps during landing operations to protecting convoys from raider and submarine attacks. During the Spanish Civil War, USS Erie evacuated U.S. citizens from the belligerent country before joining the forces at the Panama Canal, where she served until the end of her career. At the outbreak of World War II, USS Erie defended the Caribbean from German submarines.