Robert Henry Tyndall (2 May 1877 – 9 July 1947) was a United States artillery officer in World War I, a major general, and mayor of Indianapolis during World War II. Early career Robert Tyndall was born in Indianapolis, the son of William Eddy and Alice (Boyd) Tyndall. In 1897, Tyndall enlisted in Battery A of the Indiana National Guard. The Spanish–American War erupted the following year, and he served with the 27th Indiana Volunteers in Puerto Rico. Following the war, Tyndall engaged in a number of business ventures. In 1908, he married Dean Spellman, a daughter of Samuel and Emma Spellman of Indianapolis. The couple had three children. During 1915 and 1916, he served as president of the Indiana Society Sons of the American Revolution. In 1916, he sold out to his business partner and rejoined the military. World War I Tyndall served as a major in command of a battalion of the Indiana Field Artillery, which was at service on the Mexican border when the United States declared war on Germany in 1917. As the United States mobilized for World War I, the Indiana Field Artillery became federalized as the 150th Field Artillery Regiment, and assigned to the 42nd Infantry "Rainbow" Division, which participated in several major battles in 1918. Tyndall was promoted to colonel in command of the entire regiment, which was issued French 155 millimeter cannons. The men referred to him simply as "Bob," and generally admired him as an officer who had started as a private and worked his way up through the ranks. Colonel Tyndall was awarded the Distinguished Service Medal, the Croix de Guerre, and Légion d'honneur. He served in the army of occupation in Germany until 1919, where he suffered from a severe case of the flu. After recovering, Tyndall rejoined the 150th and returned to the United States, where he was honorably discharged from active service in May 1919. Tyndall returned to business, and served as vice-president of the Fletcher American Bank from 1919 to 1925. During those same years, he was the national treasurer of the American Legion, and worked to establish the organization in Indianapolis. He continued to work with several businesses in the following years. Major General Tyndall continued to serve as a colonel in the Field Artillery Officer's Reserve Corps. In 1923, he was put in command of the 38th Infantry "Cyclone" Division, and he was promoted