To meet the requirements of modern armored warfare, the regiment ended its horse-mounted operations and was reorganized on May 15, 1942, as the Second Armored Regiment. In June 1943, the unit was again restructured, designating the headquarters as the Second Cavalry Group, Mechanized, consisting of the 2nd and 42nd Cavalry Reconnaissance Squadrons. Landing in France in July 1944, the group was assigned to Lieutenant General George S. Patton's Third U.S. Army.
Operating as the reconnaissance spearhead for the Third Army, the unit conducted rapid advance-guard operations across France and Germany. During the Battle of the Bulge in December 1944, the group screened the flank of the Third Army as it pivoted north to relieve the besieged forces at Bastogne. In April and May 1945, the unit conducted a specialized operation into Czechoslovakia (Operation Cowboy) to secure and evacuate the historic Lipizzaner stallions from the hostilities of the advancing front. Separately, the regiment's 776th Amphibious Tank Battalion served in the Pacific Theater, participating in assault landings in Leyte and the Ryukyus. The regiment earned five European and two Pacific campaign streamers, along with a Presidential Unit Citation for its actions in Europe.
The mechanized cavalry group utilized a mix of specialized equipment, heavily relying on M8 Greyhound armored cars, motorized jeeps, and light tanks. Functioning as the primary intelligence-gathering asset for the corps commander, their doctrine emphasized stealth, speed, and accurate reporting. However, they frequently engaged in intense firefights to test the depth and composition of heavily fortified enemy defensive positions.
In the spring of 1945, the regiment drove deep into German territory, crossing the Rhine River and advancing rapidly into Bavaria and western Czechoslovakia. During this final push, the unit liberated multiple prisoner-of-war camps and accepted the surrender of thousands of enemy troops, playing a direct role in the systematic dismantling of the Axis war machine in Central Europe.