12th Anti-Aircraft Division was an air defence formation of the British Army during the early years of the Second World War. It defended Western Scotland and Northern Ireland, including the period of the Clydebank Blitz and Belfast Blitz, but only had a short career.

3rd Anti-Aircraft Brigade was a Supplementary Reserve air defence formation of the British Army formed in Northern Ireland in 1938. On the outbreak of the Second World War it saw active service with the British Expeditionary Force during the Battle of France and Operation Aerial. It then returned to Northern Ireland and defended the Province for the next two years. Postwar, it was reformed in the Territorial Army and served until the disbandment of Anti-Aircraft Command in 1955.