After the fall of France in 1940, the United Kingdom braced itself for invasion.
This led to the formation of the Ulster Home Guard. Men between the ages of 17 and 70 were encouraged to join. Towns and villages across the country formed companies and platoons.
By October 1939 over 27,000 had enlisted. The Ardglass platoon had two French 75mm guns left over from the Great War to defend the airfield at Bishops court. Later members of the Londonderry battalion were trained to man the anti-aircraft guns at the mouth of the Foyle.
Possible landing beaches were mined and closed off with posts and barbed wire. Machine gun emplacements were built in concrete bunkers. Many can still be seen at Tyrella, Portrush and Portstewart. The land border with the Republic of Ireland was patrolled to prevent German spies attempting to infiltrate the country.
The German plan to invade the United Kingdom was frustrated because they no longer had air superiority, after losing the Battle of Britain.
Later in the war the Home Guard manned the anti-aircraft guns at Holywood and Londonderry but never had cause to go into action.
The Ulster Home Guard was disbanded in December 1944.