Created on 1 November 1940, 9 Anti-Aircraft Division was formed by splitting off parts of 5 Anti-Aircraft Division. The Division took over responsibility for South Wales, Gloucestershire, and Herefordshire.
The re-organisation of Anti-Aircraft Command in October 1942 saw the division merged with 5 and 8 Anti-Aircraft Divisions into 3 Anti-Aircraft Group based at Bristol.
HQ Cardiff
Order of Battle 1940–41
| 5 Anti-Aircraft Brigade – from 5 Anti-Aircraft Division, covering Gloucester and Hereford |
| 85 (Tees) Heavy Anti-Aircraft Regiment (part) – from France |
| 88 Heavy Anti-Aircraft Regiment (part) |
| 47 Light Anti-Aircraft Regiment – new unit formed from part of 20 Light Anti-Aircraft Regiment |
| 37 (Tyne Electrical Engineers) Searchlight Regiment – from France |
| 45 Anti-Aircraft Brigade – from 5 Anti-Aircraft Division, covering Cardiff and Newport |
| 77 (Welsh) Heavy Anti-Aircraft Regiment |
| 85 (Tees) Heavy Anti-Aircraft Regiment (part) |
| 88 Heavy Anti-Aircraft Regiment (part) |
| 20 Light Anti-Aircraft Regiment |
| 34 Light Anti-Aircraft Regiment (part) |
| 1 Searchlight Regiment (part) – from France |
| 67 (Welch Regiment) Searchlight Regiment |
| 61 Anti-Aircraft Brigade – formed by splitting 45 Anti-Aircraft Brigade, covering Swansea and Milford Haven |
| 79 (Hertfordshire Yeomanry) Heavy Anti-Aircraft Regiment – from France |
| 34 Light Anti-Aircraft Regiment (part) |
| 1 Searchlight Regiment (part) |
| Divisional unit |
| 8 Anti-Aircraft Z Regiment – new divisional unit formed in Sep 40 |
Order of Battle 1941–42
| 5 Anti-Aircraft Brigade – to 5 Anti-Aircraft Division Jun 42 |
| 52 (London) Heavy Anti-Aircraft Regiment – from 61 Anti-Aircraft Brigade Jan 42; left Anti-Aircraft Command Feb 42; to Ceylon |
| 58 (Kent) Heavy Anti-Aircraft Regiment – from 6 Anti-Aircraft Division Autumn 41; to 4 Anti-Aircraft Division by May 42 |
| 85 (Tees) Heavy Anti-Aircraft Regiment – to 6 Anti-Aircraft Division Autumn 41 |
| 143 (Mixed) Heavy Anti-Aircraft Regiment – new unit formed Jan 42; to 67 Anti-Aircraft Brigade Jun 42 |
| 34 Light Anti-Aircraft Regiment – from 5 Anti-Aircraft Division (formerly 61 Anti-Aircraft Brigade) Mar 42; to 6 Anti-Aircraft Division Apr 42 |
| 46 Light Anti-Aircraft Regiment – from 12 Anti-Aircraft Division Jun 42 |
| 47 Light Anti-Aircraft Regiment – to 8 Anti-Aircraft Division Autumn 41 |
| 77 Light Anti-Aircraft Regiment – new unit joined Summer 41; left Anti-Aircraft Command Feb 42; to India |
| 112 (Durham Light Infantry) Light Anti-Aircraft Regiment – converted from 47 (Durham Light Infantry) Searchlight Regiment, joined before May 1942, to 61 Anti-Aircraft Brigade May 42 |
| 37 (TEE) Searchlight Regiment |
| 45 Anti-Aircraft Brigade |
| 77 (Welsh) Heavy Anti-Aircraft Regiment – left UK Dec 41, captured in Java Mar 42 |
| 79 (Hertfordshire Yeomanry) Heavy Anti-Aircraft Regiment – returned from 8 Anti-Aircraft Division Aug 42; then mobilised and left Anti-Aircraft Command; later to Operation Torch |
| 112 Heavy Anti-Aircraft Regiment – from 8 Anti-Aircraft Division Jul 41; to 61 Anti-Aircraft Brigade May 42 |
| 118 Heavy Anti-Aircraft Regiment – new unit formed Dec 40 |
| 20 Light Anti-Aircraft Regiment – began mobilisation as Defended Ports unit Aug 41; to 3 Anti-Aircraft Division Dec 41 |
| 44 Light Anti-Aircraft Regiment – from 8 Anti-Aircraft Division Autumn 41; unbrigaded by end of 41; to India 42 |
| 55 (Devon) Light Anti-Aircraft Regiment – returned from Norwegian Campaign, part of GHQ Reserve lent to Anti-Aircraft Command; left UK Nov 41, to Ceylon 42 |
| 72 Light Anti-Aircraft Regiment – from 3 Anti-Aircraft Division before May 42; to 8 Anti-Aircraft Division May 42 |
| 112 (Durham Light Infantry) Light Anti-Aircraft Regiment – from 61 Anti-Aircraft Brigade Summer 42; later to India |
| 37 (Tyne Electrical Engineers) Searchlight Regiment – from 67 Anti-Aircraft Brigade Aug 42 |
| 67 (Welch) Searchlight Regiment |
| 8 Anti-Aircraft Z Regiment – to 61 Anti-Aircraft Brigade Autumn 41; returned Aug 42 |
| 12 Anti-Aircraft Z Regiment – from 8 Anti-Aircraft Division Jun 41; to 6 Anti-Aircraft Division Autumn 41 |
| 61 Anti-Aircraft Brigade |
| 52 (London) Heavy Anti-Aircraft Regiment – joined Summer 41; to 5 Anti-Aircraft Brigade Jan 42 |
| 57 (Wessex) Heavy Anti-Aircraft Regiment – from 11 Anti-Aircraft Division May 42; to 8 Army Jun 42 |
| 79 (Hertfordshire Yeomanry) Heavy Anti-Aircraft Regiment – to 8 Anti-Aircraft Division Jun 42 |
| 112 Heavy Anti-Aircraft Regiment – from 45 Anti-Aircraft Brigade May 42 |
| 120 Heavy Anti-Aircraft Regiment – new unit formed Jan 41; to 1 Anti-Aircraft Division Autumn 41 |
| 138 Heavy Anti-Aircraft Regiment – new unit formed Nov 41; to 67 Anti-Aircraft Brigade Aug 42 |
| 34 Light Anti-Aircraft Regiment – to 5 Anti-Aircraft Division Autumn 41 |
| 50 Light Anti-Aircraft Regiment – joined Jun 42 |
| 80 Light Anti-Aircraft Regiment – from 5 Anti-Aircraft Division Dec 41; left Anti-Aircraft Command Apr 42, later to 9 Army |
| 112 (Durham Light Infantry) Light Anti-Aircraft Regiment – from the 5th Anti-Aircraft Brigade May 1942; to the 45th Anti-Aircraft Brigade Summer 1942 |
| 1 Searchlight Regiment – to 6 Anti-Aircraft Division Jan 42 |
| 77 Searchlight Regiment – joined by May 41 |
| 8 Anti-Aircraft Z Regiment – from 45 Anti-Aircraft Brigade Autumn 41; returned Aug 42 |
| 67 Anti-Aircraft Brigade – from 11 Anti-Aircraft Division Jun 42 |
| 119 Heavy Anti-Aircraft Regiment – from 8 Anti-Aircraft Division Jun 42 |
| 138 Heavy Anti-Aircraft Regiment – from 61 Anti-Aircraft Brigade Aug 42 |
| 143 (Mixed) Heavy Anti-Aircraft Regiment – from 5 Anti-Aircraft Brigade Jun 42 |
| 87 Light Anti-Aircraft Regiment – from 8 Anti-Aircraft Division Jun 42; to unbrigaded Jul 42 |
| 37 (Tyne Electrical Engineers) Searchlight Regiment – from 5 Anti-Aircraft Brigade Jun 42; to 45 Anti-Aircraft Brigade Aug 42 |