The wars revolutionised European warfare; the application of mass conscription and total war led to campaigns of unprecedented scale, as whole nations committed all their economic and industrial resources to a collective war effort. Tactically, the French Army redefined the role of artillery, while Napoleon emphasised mobility to offset numerical disadvantages, and aerial surveillance was used for the first time in warfare. The highly successful Spanish guerrillas demonstrated the capability of a people driven by fervent nationalism against an occupying force.