Early British colonists in North America needed to mobilize military power. Initially, colonists used men with previous experience to train and lead small militias. When population growth demanded more trained leaders, colonists turned to books for military knowledge. Beginning in 1690, in Massachusetts, colonists printed a series of military training manuals. Colonial publishers struggled to adapt European military knowledge to American circumstances. Initially, they reprinted European works that suffered from excessive detail and poor organization. By the 1720s, colonial books were shorter and clearer but still not well adapted to the rugged American landscape. This failure to adapt continued until the 1740s, despite some improvement. During the French and Indian War, colonists finally published books that suited American conditions. The failure to adapt sooner was due to strategic advantages that allowed American colonists to win wars with inferior tactics and to colonists' hostility to Indian warmaking techniques.