 In wartime they may be used to provide replacements for combat losses to in-action units and formations, thus allowing these to remain battle-worthy longer.They can also be used to form new units and formations to augment the regular army.In addition, reservists can undertake tasks such as garrison duty, manning air defense, internal security and guarding of important points such as supply depots, prisoner of war camps, communications nodes, air and sea bases and other vital areas, thus freeing up regular troops for the front.