Musketeers form the core of any army. Their shooting skills make their presence on the battlefield decisive, as the tide of battle may be turned by a single musket salvo. However, in melee musketeers are extremely weak against cavalry or heavy infantry, and therefore must be protected by cavalry units or pikemen. By the middle of the 16th century, most wars were fought with muskets, a weapon far more effective than its long-range predecessors, specifically the bow and the crossbow. An average person could learn to use the musket fairly quickly. The majority of low-rank musketeers were drawn from townsmen and peasants.