Let's start with the sons of U.S. Presidents. Taken from Quora https://www.quora.com/How-many-presidents-had-children-serve-in-the-military-and-during-war-time Abraham Van Buren (son of president), Mexican War Benjamin Harrison (both son and uncle of presidents), War of Texas Independence Tazewell, David, and J. Alexander Tyler (three sons of president), Civil War Richard Taylor (son of president) and John Taylor Wood (grandson of president), Civil War Robert Lincoln (son of president), Civil War Charles and Robert Johnson (sons of president), Civil War Frederick Grant (son of president), Civil War and Spanish-American War James Webb Hayes (son of president), Spanish-American War Richard Cleveland (son of president), World War I Russell Harrison (son of president), Spanish-American War Theodore Jr., Kermit, and Archibald Roosevelt (sons of T. Roosevelt), World Wars I & II Quentin Roosevelt (son of T. Roosevelt), World War I Charles Taft (son of president), World War I James, Elliott, Franklin Jr., and John Roosevelt (sons of F. Roosevelt), World War II John Eisenhower (son of president), Korean War I count 22 sons and one grandson of presidents who fought in wars. Breakdown: Martin Van Buren’s son, Abraham, was an army officer who served in the Mexican War. Benjamin Harrison, son of President William Henry Harrison and uncle of President Benjamin Harrison, fought in the War for Texas Independence. (See President Benjamin Harrison below.) John Tyler had 14 children who lived to maturity—more than any other president. John Jr. was Asst. Secretary of War under the Confederacy and three sons joined the Confederate Army. One, Tazewell, was an army surgeon. (Yet another son, Lachlan, served as a surgeon in the U.S. Navy, but that was well after the Civil War.) Zachary Taylor’s son, Richard Taylor, served in the Mexican War and in the Civil War as a Confederate general. In fact, he was the last general to surrender to the Union in May 1865. But there’s more! The president’s daughter, Sarah, married a soldier named Jefferson Davis who became president of the Confederacy. Another, Ann, married a U.S. Army surgeon and their son, John Taylor Wood, a grandson of the president, also joined the Confederate Army. Robert Lincoln, son of President Abraham Lincoln graduated from Harvard University in 1864, and only then joined the Union Army, serving on the staff of Gen. Ulysses S. Grant during the last weeks of the Civil War. Two of Andrew Johnson’s sons, Charles and Robert, served the Union during the Civil War. Charles died in a service-related accident. President Grant’s son, Frederick, was barely a teen when he was wounded at the Civil War Battle of Vicksburg. (Officially a noncombatant, he was tagging along with his father.) He later became a general during the Spanish-American War. President Rutherford Hayes’ son, James Webb Hayes, served as an officer during the Spanish-American War and won the Congressional Medal of Honor. Richard F. Cleveland, son of Grover Cleveland, served as an officer in the U.S. Marines during World War I. The son of President Benjamin Harrison was Russell Harrison, who served as an officer during the Spanish-American War. The wartime service of four of Theodore Roosevelt’s sons ought to be better known. They were Theodore Jr., Kermit, Archibald, and Quentin. Three of them served in both World Wars I and II, Theodore earning four U.S. medals and Archibald earning at least two. Theodore and Kermit died of natural causes during World War II. Archibald was wounded and discharged during World War II. Quentin died in combat during World War I. President William H. Taft’s second son, Charles P. Taft, was an officer in the U.S. Army during World War I. Franklin Roosevelt’s four sons served as officers during World War II: James in the Marines, Elliott in the Army Air Corps (predecessor of the Air Force), and Franklin Jr. and John A. in the Navy. Elliott’s rapid rise from captain to general was thought by some to reek a bit of favoritism, but the other brothers seem to have served with distinction. James was decorated for saving the lives of fellow Marines. President Dwight Eisenhower’s son, John, served as in officer during World War II and the Korean War. He did not see combat during the first conflict but did in the next.