During World War II, we transferred 50 U.S. destroyers to the British in exchange for naval bases in several British colonies. The British needed the destroyers to help combat the threat from German U-boats. We were still neutral, so we had to come up with a way to give the British the destroyers without breaching neutrality under international law. Since the British gave us something in return, they legally "bought" the ships and the Germans were still required to respect our neutrality.