Was Operation Diadem or the Battle of Cold Harbor fought during the Civil War?
Operation Diadem Operation Diadem, also referred to as the Fourth Battle of Monte Cassino or, in Canada, the Battle of the Liri Valley, was an offensive operation undertaken by the Allies of World War II (U.S. Fifth Army and British Eighth Army in May 1944, as part of the Italian Campaign of World War II. "Diadem" was supported by air attacks called Operation Strangle. The opposing force was the German 10th Army.
Battle of Gaines's Mill The Battle of Gaines's Mill, sometimes known as the First Battle of Cold Harbor or the Battle of Chickahominy River, took place on June 27, 1862, in Hanover County, Virginia, as the third of the Seven Days Battles (Peninsula Campaign) of the American Civil War. Following the inconclusive Battle of Beaver Dam Creek (Mechanicsville) the previous day, Confederate General Robert E. Lee renewed his attacks against the right flank of the Union Army, relatively isolated on the northern side of the Chickahominy River. There, Brig. Gen. Fitz John Porter's V Corps had established a strong defensive line behind Boatswain's Swamp. Lee's force was destined to launch the largest Confederate attack of the war, about 57,000 men in six divisions. Porter's reinforced V Corps held fast for the afternoon as the Confederates attacked in a disjointed manner, first with the division of Maj. Gen. A.P. Hill, then Maj. Gen. Richard S. Ewell, suffering heavy casualties. The arrival of Maj. Gen. Stonewall Jackson's command was delayed, preventing the full concentration of Confederate force before Porter received some reinforcements from the VI Corps.