Boeing Co. won an $805 million contract on Thursday to develop the first unmanned plane for Navy aircraft carriers, a tanker drone that can refuel fighter jets in mid-flight.

The initial agreement covers development of four aircraft, which are expected to be complete in August 2024, the U.S. Defense Department said in a statement. The Chicago-based planemaker, which intends to do the work in St. Louis, was one of three companies that submitted bids for the project; its rivals were General Atomics and Lockheed Martin.