The Jolly Roger is a symbol that has been used by submarines, primarily those of the Royal Navy Submarine Service and its predecessors. The practice came about during World War I: remembering comments by First Sea Lord Admiral Sir Arthur Wilson, who complained that submarines were "underhanded, unfair, and damned un-English" and that personnel should be hanged as pirates, Lieutenant Commander Max Horton began flying the flag after returning from successful patrols. Initially, Horton's submarine HMS E9 flew an additional flag after each successful patrol, but when there was no room for more, the practice was changed to a single large flag, onto which symbols indicating the submarine's achievements were sewn.