American Civil War | Georgia | Vietnam War | Georgia (U.S. state) | American Revolutionary War | Cold War | Iraq War | War of 1812 | Spanish Civil War | Georgia (country) | Korean War | Allies of World War II | English Civil War | Gulf War | Franco-Prussian War | Pacific War | war | Second Boer War | University of Georgia | Peninsular War | Savannah, Georgia | United States Department of War | Second Sino-Japanese War | Crimean War | Thirty Years' War | Spanish-American War | Trojan War | Georgia Institute of Technology | International Civil Aviation Organization | Union (American Civil War) |
During the American Civil War McMillan had served in the Georgia 3rd Battalion, Sharpshooters, commanding Company B. He was elected in 1874 as a Democrat to represent Georgia's 9th congressional district in the 44th United States Congress.