503rd
503rd Infantry Regiment (United States)
503rd Heavy Panzer Battalion
1st Battalion, 503rd Infantry Regiment
2nd Battalion, 503rd Infantry Regiment
503rd Marine Battalion (Ukraine)
501e-503e Régiment de chars de combat
103rd SS Heavy Panzer Battalion
703rd Strategic Missile Wing
Forth Royal Garrison Artillery
503rd Air Defense Group
503rd Aircraft Control and Warning Group
List of German brigades in World War II
1st Somersetshire Engineers
1st Middlesex Engineers