E. P. Alexander, known to his friends as Porter, graduated from the United States Military Academy at West Point in 1857, third in his class of 38 cadets, and was brevetted a second lieutenant of Engineers. At West Point he participated in a number of weapons’ experiments and worked as an assistant to Major Albert J. Myer, the first U.S. Army Signal Officer. Alexander’s final assignment for the U.S. Army was in the Washington Territory at Fort Steilacoom and at Alcatraz Island near San Francisco, California.
After learning of the secession of his home state of Georgia, Alexander resigned his U.S. Army commission on May 1, 1861, to join the Confederate Army as a captain of engineers. He became the Chief Engineer and Signal Officer of the (Confederate) Army of the Potomac on June 3, 1861. At the First Battle of Bull Run, he made history by transmitting the first message in combat using signal flags over a long distance. Stationed atop “Signal Hill” in Manassas, Alexander saw Union troop movements and signaled to the brigade under Col. Nathan Evans, “Look out for your left, your position is turned”, which meant that they were in danger of being attacked on their left flank. Upon receiving a similar message, Gens. Beauregard and Joseph E. Johnston sent timely reinforcements that turned the tide of battle in the Confederates’ favor.
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