Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost.
The turning point of the Pacific Campaign of World War II was the naval Battle of Midway, which occurred between June 4 and June 7, 1942.
Antietam was the major turning point of the Civil War. See also Civil War Turning Point: A List of Major and Pivotal Turning Points. The battle was fought on Wednesday, September 17, 1862, and less than 3 weeks after the costly Confederate victory at the Second Battle of Manassas (aka Second Bull Run).