This cover has a bit of a war theme to it as the stamps were issued to commemorate wars, battles, and those lost in the line of duty.
The first, leftmost stamp shows a depiction of the rescue of the Lusitania by the wanderer, a fishing boat. The RMS Lusitania was an ocean liner owned by the Cunard Line and built by John Brown and Company on 7 May 1915 and sank in eighteen minutes, eight miles off the of Clydebank, Scotland. She was torpedoed by German U-boat U-20Old Head of Kinsale, Ireland, killing 1,198 of the 1,959 people aboard. The sinking turned public opinion in many countries against Germany, and was instrumental in bringing the United States into World War I. The sinking of the Lusitania was a coup for anti-German sentiment and caused great controversy.
More information on the Lusitania and its terrible fate here and here.
The next two stamps to the right are from a 4v set issued in 1981 to commemorate the 60th anniversary of the Royal British Legion.
The upper stamp pays homage to Major Robert Henry Cain VC (2 January 1909 – 2 May 1974), a Manx recipient of the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.
Cain grew up on the Isle of Man and joined the Territorial Army in 1928. After working overseas he was given an emergency commission into the Army in 1940. He saw action during the Invasion of Sicily in 1943 and again during the Battle of Arnhem the following year. During the battle Major Cain's company was closely engaged with enemy tanks, self-propelled guns and infantry. Cain continually exposed himself to danger while leading his men and personally dispatched as much enemy armour as possible. Despite sustaining several injuries he refused medical attention and for his gallantry he was awarded the Victoria Cross.
The stamp on the far right shows one of six stamps issued to to commemorate the 90th anniversary of the end of World War 1 and the personal contributions of a selection of local soldiers.
This particular stamps features Pte Joseph Killey was born in Ramsey, the son of a carpenter. In 1915 he enlisted in the Lancashire Fusiliers. He was posted to the 2nd Battalion and was soon serving with them in Belgium. He was killed in action on July 8, 1915 during the Battle of Boesinghe where British troops had taken over a stretch of front line from the French.
See the entire set here.