These bomb loads ranged from small 100 kg bombs in 1939 to the 10,000 kg Grand Slam in 1945. Each bomber in a squadron had its own groundcrew, and it was the armourers responsibility to organize the bomb stores before each mission. The armourer prepared the bomb loads and then fused the bombs on their trolleys before driving them out to the individual aircraft.

With constant demand for more advanced bomb technology including Sea Mines, Torpedoes, Incendiaries and Bouncing Bombs (used by the Dam busters), armourers had to stay informed of the latest bomb types and the methods of fusing them. They were also responsible for defusing any bombs that were brought back on returning aircraft but failed to drop, or were scattered about a runway after a bomber crashed on takeoff or landing.

History tells us that during the Second World War our bomber crews put their lives on the line each time they climbed aboard their aircraft in preparation for that night flight over enemy territory. They had to fly to their destination through enemy gunfire both from the air and ground, find their assigned target, drop their bombs, then fight their way back home to England. The bravery of these men should never be forgotten, for theirs was a formidable task.

But how did the bombs get in the aircraft? Who places them there? What kind of weapons were they? How were they armed? How much did they weigh? These are all thought provoking questions when one looks behind the scenes. The men that carried out the task of bombing-up were known as Armourers. There were Gun Armourers, Turret Armourers and Bomb Armourers.

The Bomb Armourers had a very labour intensive and potentially dangerous job. Bombs were stored in a bomb dump and in simple terms were a cylindrical piece of steel filled with a high explosive composition. They were aerodynamically designed and came in many different weights and configurations. The bombs most commonly used were high explosive 250, 500 and 1,000 pounders.

In preparing these weapons, the Armourers first loaded them on a bomb trailer which was a low-slung vehicle that could be easily manoeuvred under the aircraft fuselage. Each trailer carried 1 to 8 bombs depending on the weight and size of the chosen weapon. Once the bombs were on the trailer the Armourers then had to attach a tail fin to each weapon to make it more aerodynamic and stabilize its flight from the aircraft to the target.

This completed, the next step was to remove a nose and/or tail plug and insert a special fusing device that would be programmed to detonate the bomb at a predetermined level above the ground. Contrary to popular belief, all bombs did not hit the ground and then detonate. The bomb fusing devices could be timed – set to explode at a predetermined time after leaving the aircraft.

Bombs could also be set to detonate at a predetermined atmospheric pressure, or proximity to detonate near the assigned target. Each fuse had a safety pin installed which connected to a short wire cable with a loop in the other end. These tasks completed a tractor (called a mule) would hook up to the trailer train and move off to the dispersal area for loading in the designated aircraft.

For example, the Lancaster Mk X, flown by Canadian airmen, could hold approximately thirty 500 pound (230 kg) bombs. The bomb train was carefully manoeuvred under the aircraft bomb bay so the bombs could be winched into position and the bomb loading lugs locked into the shackles of the respective bomb rack. To accomplish this, an Armourer has to set up a bomb winch on the floor inside the bomber, and directly over the position where the bomb will be stored. A thin steel cable was then lowered through an opening in the floor and attached to the bomb below.

The armourer, on his knees, then commenced the laborious task of hand winching each bomb 12 to 15 feet into its bomb bay position. Once all the bombs were loaded, the fuse cable would be attached to the bomb rack so when the Bomb Aimer released his bomb load over the target, the safety pin would be pulled out as the bomb fell free from the aircraft, thus commencing the arming process. Now that the bombs are all in place the bomb bay doors could be closed and the aircraft ready for its flight to the target area many miles away.

The Lancaster was also capable of carrying three gigantic specialty bombs in the centre line position of the bomb bay. The first developed was the 4,000 pound "Cookie" or blockbuster bomb. The next was a 12,000 pound (5,400 kg) "Tallboy" one which was used to sink the German battleship Tirpitz while it was anchored in a Norwegian fjord in November 1944.

In order to carry the Tallboy the Lancaster bomb bay doors had a contour modification so the doors could fit snugly around the bomb. With a normal bomb load the doors would close tightly, but because of the girth of the Tallboy they could only be partially closed. The heaviest bomb of all was the 22,000 pound (10,000 kg) Grand Slam of which 40 were delivered to various targets in Europe before the war ended. In order to carry the huge Grand Slam the bomb bay doors had to be removed.

Of the 7,300 Lancasters built, half would be lost during operations. Between 1942 and 1945 they would fly 156,000 sorties and drop over 600,000 tons of bombs on enemy targets.