Although mounted troops or cavalry were key in early Rome, they became of critical importance after the introduction of the stirrup. The stirrup provided the rider with enough leverage to allow him to charge with a lance without being thrown from his saddle. However with the introduction of gunpowder, mounted knights became vulnerable: they were easy targets for musketeers. In response to this threat, military strategists were forced to come up with new tactics, thus advancing the efficacy of cavalry.