Cavalry found a new role in colonial campaigns (irregular warfare), where modern weapons were lacking and the slow moving infantry-artillery train or fixed fortifications were often ineffective against indigenous insurgents (unless the latter offered a fight on an equal footing, as at Tel-el-Kebir, Omdurman, etc.). Cavalry "flying columns" proved effective, or at least cost-effective, in many campaigns—although an astute native commander (like Samori in western Africa, Shamil in the Caucasus, or any of the better Boer commanders) could turn the tables and use the greater mobility of their cavalry to offset their relative lack of firepower compared with European forces.