Crittenden's career as an elected official began in the Kentucky House of Representatives, where he represented Logan County from 1811 to 1817.[9] After the 1811 legislative session, he volunteered as an aide to General Samuel Hopkins in an expedition against the Indians.[15] On the outbreak of the War of 1812, Kentucky governor Charles Scott appointed him as an aide-de-camp for the First Kentucky Militia.[1] In 1813, he became an aide-de-camp to Governor Isaac Shelby, serving at the Battle of the Thames in Canada.[16][17] Following the war, the governor issued him a special commendation for faithfulness in carrying out his orders.[1] He then resumed his law practice in Russellville.[9]