The M10 Tank Destroyer and M4 Sherman: The Difference in Capabilities

During a recent visit to the Patton Museum with my two sons, I took special notice of the M10 tank destroyer and the M4 Sherman, both of which are displayed inside the museum. I knew the M10 was used in the early days of World War II by the United States and Great Britain; however, I did not realize the similarity in the diameter of these two main guns. On further inspection of both gun tubes, they appeared to be the same size, but how can a tank destroyer have the same main gun size as an M4 Sherman? I further read the signs displayed at each vehicle and realized the M10 has a 3-inch (M7) main gun and the M4 Sherman has a 75mm M3 L/40 main gun. Being curious about the exact difference in the two main guns, I did some research and discovered a difference of 1.2 mm in liberately separated from the existing combat arms.”1 The M10 gun motor carriage (GMC) replaced the M3 self-propelled 75mm halftrack vehicle as a tank destroyer. “The vehicle mounted a 3-inch gun in an open-topped turret. It entered service in the latter half of 1942 and entered combat in March 1943. The main armament’s gun sight and armor penetration ability surpassed that of the M4 Sherman medium tank, but the longer range of the 3-inch gun encouraged crews to exaggerate its performance.”2 Even so, I still wondered why the United States created a tank destroyer that, performance wise, was only slightly better than an M4 Sherman, thus leading me to the history of the main gun of the M10 GMC. “In September 1940, a project was started to adapt the 3-inch gun to the antitank role, starting with the T9 experimental model, but equipping it with the breech, recoil system, and carriage borrowed from the 105mm M2 howitzer. This was accepted for service as the 3-inch M5. A final adaption was the 3-inch M7, which included minor modifications for mounting on the M10 GMC.”3 In June 1942, the M10 was ordered into full production. During its combat debut in Tunisia in 1943, the M10 was successful and could destroy most German tanks in service. Later, during the Battle of Normandy, the M10’s gun proved to be ineffective against frontal armor of the new German Tiger and Panther tanks.4 After reading about U. S. tanks in the 1940-1942 timeline, it became obvious that a 3-inch gun probably seemed like a large-caliber weapon to mount on a tank destroyer. M4 Sherman The M4 Sherman’s main gun was the short-barreled, medium-velocity 75L24- mm M3 gun. In late 1942, when the Sherman first saw combat in North Africa, against Panzer III and Panzer IV tanks, its gun could penetrate the armor of these tanks at normal combat ranges. The U. S. Army intelligence discounted the arrival of the Tiger I (late 1942) and Panther tanks (1943), predicting they would be produced only in small numbers. The U. S. Army failed to foresee that the German army would make the Panther the standard tank of its panzer divisions by 1944, supported by substantial numbers diameter. In other words, the M10 boasted a 3-inch (76.2mm) main gun, while the M4 Sherman had a 75mm main gun. But, I still wasn’t satisfied — why would a tank destroyer have a main gun only 1.2mm larger than an M4 Sherman, which was obviously outclassed when met by a German Panther or Tiger tank on the battlefields of France in 1944. M10 Tank Destroyer “Army combat preparations anticipated the battlefield presence of large German armored formations similar to those used to overrun much of Europe and Russia. Therefore, the War Department established a tank destroyer force to nullify the German tank threat. Tank destroyers represented anew concept, and responsibility for their development was thus de-Above, an M10 Wolverine tank destroyer sees action near St. Lo, France, June

1944. At left, an M10 in North Africa, 13 March 1943. 43 of Tigers.5 The increased frequency of armored battles generated interest in increasing the M4’s firepower; some M4 variants were fielded with 76mm guns, but the potential value of this weapon was partially nullified by the extensive muzzle blast and smoke that surrounded its discharge, thereby identifying the tank’s position.6 The Slight Difference The M10 main gun is a converted M1918 coastal-defense, 3-inch antiaircraft gun mounted on an “M4A2 chassis and replaced the circular turret with a pentagonal version.”7 Although slightly larger than the M4’s 75mm main gun, the 3-inch main gun on the M10 performed only slightly better on the battlefield in North Africa, not to mention that the speed doctrine producers were expecting from a tank destroyer was disappointing. During the battles of Normandy, European theater commanders wanted a tank with a larger caliber weapon that could kill another tank; specifically, the Panther and Tiger. This request was answered, “In response to the growing concerns from the combat theaters about the inferiority of American tanks, the Ordnance Department undertook the independent development of a more powerful tank armed with a 90mm gun. Ultimately, this project became the M26 Pershing heavy tank, which entered combat in the final weeks of the war.”8 As I read history, the M10 GMC was the best the U. S. Army had, based on then-current tank destroyer doctrine, to destroy large columns of smaller German tanks. What the armor corps had at the time was a 3-inch main gun, which until 1944, could penetrate most German tanks on the battlefield. Complemented with the 75mm main gun of the M4 Sherman, the M4 and M10 were a lethal one-two punch on the battlefield of North Africa, Sicily, and Southern Italy from 1942 to 1944. Notes 1Robert S. Cameron, Mobility, Shock, and Firepower: The Emergence of the U. S. Army’s Armor Branch, 1917-1945, U. S. Army Center of Military History, Washington, D. C, p. 405, 2008. 2Ibid. 3Wikipedia, “3-Inch Gun M1918,” available online at http:// en.wikipedia.org/wiki/3-inch_Gun_M1918. 4Wikipedia, “M10 Tank Destroyer,” available online at http:// en.wikipedia.org/wiki/M10/Wolverine. 5Wikipedia, “M4 Sherman,” available online at http://wikipedia.org/wiki/M4_Sherman. 6Mobility, Shock, and Firepower: The Emergence of the U. S. Army’s Armor Branch, 1917-1945, p. 462. 7Wikipedia, “M10 Tank Destroyer.” 8Mobility, Shock and Firepower, The Emergence of the U. S. Army’s Armor Branch, 1917-1945, p. 463. Lieutenant Colonel Scott K. Fowler is serving as the special assistant to the commanding general, Office of the Special Assistant to the Commanding General, Fort Knox, KY. He received a B. A. from Northern Kentucky University. His military education includes the U. S. Army Command and General Staff College, the Armor Officer Basic and Advanced Courses, and Combined Arms and Services Staff School. He has served in various command and staff positions, to include executive officer, 4th Battalion, 85th Training Support Brigade (4/85 TSB), Fort Knox, KY; plans officer, 4/85 TSB, Fort Knox; S3, 103d Chemical Battalion, Kentucky Army National Guard (KYARNG); commander, University of Kentucky, Army Reserve Officer Training Corps (ROTC), Lexington, KY; company commander, 3d Battalion, 123d Armor, KYARNG; platoon leader, A Troop, 1st Squadron, 4th Cavalry, 1st Infantry Division (Forward), Boeblingen, Germany; and tank platoon leader and company XO, C Company, 4th Battalion, 37th Armor, 2d Brigade, Fort Riley, KS. The crew of an M26A3 tank from the 14th Battalion, 9th Armored Division, awaits attack orders in afield on the outskirts of Vettweiss, Germany, 1 March 1945. Above, a tank crew checks its M4A1 after landing at Red Beach 2 in Sicily on 10 July 1943. At left, a 1st Tank Battalion, 1st Armored Division M4 crosses the Arno River near Casoina, Italy, in September 1944. 44