Alfred Edward Waldo was born around 1844 in Massachusetts to William and Mary Waldo. His father was a bootmaker who owned $1,500 of real estate by 1850. Waldo grew up and attended school in Stoughton, Massachusetts, and by the early 1860s, he was working as a farmer.
He enlisted in the Union army on August 11, 1862, and he mustered in as a private in Company E of the 35th Massachusetts Infantry on August 19. According to his service records, he was 6 feet, ½ inch tall, with brown hair and hazel eyes. The regiment took part in the Battle of Antietam, the Battle of Fredericksburg, the siege of Vicksburg, the Knoxville campaign, and the Overland Campaign. He was severely wounded in the Battle of Spotsylvania Court House on May 18, 1864, and surgeons amputated his left arm. He died in Washington, D.C., on June 7, 1864.