Daniel Chaplin (January 22, 1820 – August 20, 1864) was a Union army officer in the American Civil War. Under Chaplin's command, the ill-fated charge of the 1st Maine Heavy Artillery Regiment against Confederate breastworks during Siege of Petersburg resulted on the greatest single loss of life by a Union Regiment in a single action. A total of 7 officers and 108 men were killed, and another 25 officers and 464 men wounded. These casualties constituted 67% of the strength of the 900-man force. Chaplin survived the action but while supervising pickets on August 17, 1864, the day after the Battle of Deep Bottom, he was shot by a Confederate sharpshooter, and he died four days later in a Philadelphia hospital.