13 Anti-Tank Regiment RA was formed by the conversion of 13 Field Brigade RA with four batteries in May 1938. The Regiment moved to North Africa in June 1942. It served in the Middle East and Italy in various Army Groups RA and under 5th and 10th Indian Divisions. In April 1947 13 Anti-Tank Regiment RA was re-designated 20 Anti-Tank Regiment RA.
Illustrations of the formation badges under which a unit served or supported are given. This is no guarantee that the unit used this formations badge.
| 3 Sep 39 |  |
2 Infantry Division | Aldershot, Hampshire, UK |
| Sep 39 | |
2 Infantry Division | France |
| Jun 40 |  |
2 Infantry Division | UK |
| Jul 41 | |
2 Infantry Division | Holme, Yorkshire, UK |
| Jun 42 |  |
GHQ Middle East Forces | N Africa |
| Aug 42 |  |
5 Indian Division | N Africa |
| Oct 42 | |
5 Indian Division | Iraq |
| Apr 43 |  |
9 Army | Iraq |
| May 43 | 7 Army Group RA | Syria | |
| July 43 |  |
10 Indian Division | Palestine |
| Mar 44 | |
10 Indian Division | Italy |
| Aug 45 |  |
2 Army Group RA | Italy |
Batteries
| 3 Sep 39 | 2, 8, 44, 82 |
| Sep 41 | 44 Battery to 84 Anti-Tank Regiment on formation Returned Oct 41 |
| Late 41 | 2 Battery to 80 Anti-Tank Regiment on formation |
| Aug 42 | 8, 44, 82, 100 |
| Mar 45 | 8, 44, 82, 314 |