Memorial Day celebrations in the United States began after the Civil War to commemorate the lives of those lost during the war. During FDR’s presidency, Decoration Day honored the lives of all Americans who had died in military service for the United States. The name of the holiday was officially changed to Memorial Day in 1967 and starting in 1971 the date was moved from May 30th to the last Monday in May.
In 1936, FDR received the following message from King Leopold III of Belgium in observance of Decoration Day.
This document and others from the collections of the FDR Library can be found on the Franklin D. Roosevelt Day by Day website.