h ese increases in the weight and protective qualities of armor quite naturally made some of the weapons wielded by earlier medieval cavalrymen impractical. Because wearing plate armor reduced a riderís l exibility of movement, for instance, he no longer used the bow or spear. His chief weapons instead became the sword and lance. Cavalry swords grew longer and heavier than ever before, and lances ranged from 10 to 12 feet (3 to 3.6 m) in length and featured a l ared section in the rear to protect the knightís hands and forearms. Working in tandem with stirrups and advances in armor, the improved lance was a key factor in the emergence of the massive, destructive cavalry charges depicted in modern books and movies. Still another factor that made such tactics possible was the introduction of big, sturdy, wraparound saddles in about 1100. h e horseman rested the back of his lance against the saddleís pommel (an upright knob made of wood and leather). h is absorbed much of the force caused by the impact of crashing into an enemy line. Modern military historians call this formidable use of lance and saddle the ďcouched lance technique.Ē Military commanders took full advantage of these advances. h ey were now able to use their units of knights as one of several dif erent arms systems that combined during an attack on an opposing army. Ideally, a commanding general i rst ordered his archers to soften up the enemy, killing some and tiring the others. h en his knights lowered their lances and charged the opposing lines, shattering them, or at least pushing them back and creating gaps in their ranks. Finally, he sent his own soldiers into those openings, in so doing bringing fresh troops to bear against the exhausted enemy infantry. Meanwhile, that generalís heavy cavalry turned around and assaulted the opposing army from the rear. Not every battle progressed in this exact manner. But these were the basic arms systems and tactics that each commanding general took onto the i eld and used in various ways in hope of gaining the advantage. Not surprisingly, the ef ectiveness of a generalís army depended in large degree on how many wellequipped, experienced i ghters, particularly knights, he could muster. h e number of knights in a given nation or region varied widely. So did the amount of battle experience they had accumulated. For example, evidence suggests that roughly i ve thousand knights existed in England at any given time during the century and a half following the i ght at Hastings in 1066. But not all of these heavy cavalrymen took part in any single military campaign or battle. h e eleventh-century English chronicler Oderic Vitalis reported that a powerful noble named William Rufus was alone able to mobilize some seventeen hundred knights for a military campaign in 1098. At i rst glance that number may seem small. After all, it represented only about a third of the knights in the kingdom. Yet compared to how many knights took part in each of the campaigns of the period in question, the number that Rufus mustered turns out to be unusually large. Much more typical was the force of i ve hundred knights that King Henry II took with him on a campaign in Ireland in 1171.