Charles Ellet Jr. was an American civil engineer and inventor, born on February 1, 1810. He is best known for his work on the design and construction of bridges, particularly the Potomac River bridge at Washington, D.C.. Ellet was a pioneer in the use of iron in bridge construction, which significantly advanced engineering practices of his time. In addition to his contributions to bridge engineering, Ellet was involved in the development of the United States military during the Civil War. He designed several military structures and was appointed as a chief engineer for the Union Army. His innovative approaches helped improve military logistics and infrastructure during the conflict.