Though early man probably employed spears of fire-hardened wood, spearheads of knapped stone were used long before the emergence of any distinction between hunting and military weapons. Bronze spearheads closely followed the development of alloys hard enough to keep a cutting edge and represented, with the war ax, the earliest significant military application of bronze. Spearheads were also among the earliest militarily significant applications of iron, no doubt because existing patterns could be directly extrapolated from bronze to iron. Though the hafting is quite different, bronze Sumerian spearheads of the 3rd millennium BC differ only marginally in shape from the leaf-shaped spearheads of classical Greece. The spears of antiquity were relatively short, commonly less than the height of the warrior, and typically were wielded with one hand. As defensive armor and other weapons of shock combat (notably the sword and mounted troops) improved, spear shafts were made longer and the use of spearmen became increasingly specialized. The Greek hoplite's spear was about nine feet long; the Macedonian sarissa was twice that length in the period of Alexander's conquests. The Middle Ages would see the evolution of the spear into the pike and halberd.