Some but not all landing craft were armed. They can be divided into two categories. Fire support landing craft generally did not carry troops but had the primary role of firing their weapons against enemy forces, to assist friendly troops ashore. These craft ranged from small types armed with machine guns, mortars and/or rockets, such as the LCS(S), LCS(M) or LCA(HR), to larger vessels based on the hull of an LCT. The latter included the LCG(L) which had two 4.5-inch guns, or the types fitted to many destroyers, and the LCT(R) which was armed with around 1,000 rocket-projectors.
Above: A pair of Royal Canadian Navy LCI(L)s alongside each other, off Juno Beach on D-Day. The 20mm Oerlikon in the bow of each craft can be clearly seen. This weapon was useful for both anti-aircraft and anti-shipping defence. On D-Day some landing craft crews also fired Oerlikons against the enemy beachfront defences in support of Allied troops. (Photo: Canada. Department of National Defence / Library and Archives Canada)
While larger warships provided the majority of fire support in amphibious landings, these smaller armed landing craft had a much shallower draught. They could get closer inshore than warships and thus provide critical support to the assault troops.
The second category is troop-carrying landing craft that were armed for self-defence. For example, LCTs often had a pair of 20mm Oerlikon guns or 2-pounder guns, while LCI(L)s were fitted with up to five 20mm Oerlikons. These weapons were primarily for defence against attacks by enemy aircraft or shipping (such as E-boats), but on D-Day they were sometimes used to fire on German beachfront positions. British-built LCTs might have Parachute and Cable (PAC) or Fast Aerial Mine (FAM) for anti-aircraft use. Smaller craft such as LCVPs or LCAs sometimes had one or two machine guns which could be fired on enemy positions as the vessel beached. In an emergency, the weapons of the troops on board could even be used.