The United States Exploring Expedition was an exploring and surveying expedition of the Pacific Ocean and surrounding lands conducted by the United States from 1838 to 1842. The original appointed commanding officer was Commodore Thomas ap Catesby Jones. The voyage was authorized by Congress in 1836. It is sometimes called the "U.S. Ex. Ex." for short, or the "Wilkes Expedition" in honor of its next appointed commanding officer, United States Navy Lieutenant Charles Wilkes. The expedition was of major importance to the growth of science in the United States, in particular the then-young field of oceanography. During the event, armed conflict between Pacific islanders and the expedition was not uncommon and dozens of natives were killed in action, as well as a few Americans.