Term | Explanation |
| H2S | British airborne radar used for identifying and locating ground targets. |
| Heer | German Army. |
| Herbstnebl | Autumn Mist - Operational code name for the German offensive in the Ardennes, December 1944 - Also known as The Battle of the Bulge. |
| HIWI | Hilfsfreiwillige - German Army volunteer forces usually made up of Soviet volunteers |
| Holocaust | The act of genocide carried out by Germany on the Jewish population of Europe. |
| Huff-Duff | HF/DF - High Frequency / Direction Finding - British radio detection system used to pinpoin the direction of broadcasts from German submarines and ships and thus locate the transmitting craft. |
| Humint | Human Intelligence - Intelligence gathered by spies and informers (as opposed to signals intelligence or SIGINT). |
| Husky | Operational code name for the Allied landings in Sicily - July 1943. |