| 4th Motor Brigade | |
|---|---|
&sq=Facebook&lang=en&file=File:4th_Cavalry_Brigade_at_Wallgrove_1940_(AWM_image_P02835007).JPG) On exercise near Wallgrove, February 1940 | |
| Active | 1921–1942 |
| Country |  Australia |
| Allegiance | Australian Crown |
| Branch | Australian Army |
| Type | Cavalry (1921–1942) Motorised infantry (1942) |
| Size | Brigade |
| Part of | 1st Cavalry Division 1st Motor Division |
| Insignia | |
| Unit colour patch | &sq=Facebook&lang=en&file=File:Headquarters_4th_Light_Horse_Brigade.png) |
The 4th Motor Brigade was a formation of the Australian Army during the interwar years and the early part of the World War II. A formation of the part-time Militia, the brigade was formed in 1921 as the 4th Cavalry Brigade. At this time, it consisted of three light horse regiments based in southern and western New South Wales. During World War II, the brigade was mobilised for defensive duties in December 1941, and assumed positions along the southern New South Wales coast to defend against a possible invasion. It was converted into the 4th Motor Brigade in March 1942 when it was motorised. As a motor brigade, the 4th undertook defensive duties on the south coast of New South Wales before it was converted into an armoured formation, designated the 3rd Army Tank Brigade in May 1942.