Because of the violent, physical way in which football games were conducted in the 19th century, many deaths and maiming injuries occurred. As a result of 18 deaths and 159 serious injuries in 1905, President Theodore Roosevelt insisted that the colleges make their game safer or he might ban it. Representatives of 62 colleges met in New York City after the 1905 season, and in early 1906 rules were suggested and approved that would eliminate the negative aspects. The emphasis was shifted from brawn to speed and strategy. The legalization of the forward pass made much of this possible. The game was also shortened from 70 to 60 minutes, and the required yardage for a first down was reset at 10 yd. A neutral zone was set up between teams at the scrimmage line, and the offense had to have at least six men on the line of scrimmage, thus eliminating the dangerous plays in which blockers took running starts before the snap of the ball. A seventh blocker on the line of scrimmage was mandated in 1910 to make the game even safer. Football rules were changed constantly, however, to maintain the delicate offense-defense balance. After 1912, however, when the number of chances to make a first down was increased to four, the changes were less drastic.