 Ramba uchiverenga ndima iyi - Cooke akagadzwa kuva mukuru mukuru wemauto, U.S. Army, musi waNovember 21, 1861, kuti ave nomukurumbira kubva musi waNovember 12, 1861. Mutungamiri Abraham Lincoln akasarudza Cooke nokuda kwekugadzwa musi waDecember 21, 1861 uye Seneti yeUnited States yakasimbisa musi waMarch 7, 1862. Pakutanga akatungamira brigade yemauto enguva dzose emauto mukati mekudzivirirwa kweWashington, D.C. Kune Peninsula Campaign, akasarudzwa naMcClellan kuti atungamire Cavalry Reserve, divi-saizi simba, reArmy of the Potomac. Apo mauto eConfederate akabvisa guta reYorktown, Cooke akatumirwa pamwe naMajor General George Stoneman mukutsvaga uye vatasvi vake vakaurayiwa mukurwisa kwakarairwa naStoneman pamusoro peFort Magruder. Akaona chiito chakatevera muhondo dzeWilliamsburg, Gaines Mill, uye White Oak Swamp. Cooke akarayira kurwisa kwakashata kwe5th U.S. Cavalry paGaines Mill panguva yeSeven Days Battles, achibayira rinenge regiment rose revarwi. 