Hyatt joined the 127th Illinois Infantry in August 1862, and was discharged in March 1865 for a wound received during the Atlanta Campaign.

[1] On May 22, 1863, General Ulysses S. Grant ordered an assault on the Confederate heights at Vicksburg, Mississippi.

The plan called for a storming party of volunteers to build a bridge across a moat and plant scaling ladders against the enemy embankment in advance of the main attack.

The volunteers knew the odds were against survival and the mission was called, in nineteenth century vernacular, a "forlorn hope".

Despite repeated attacks by the main Union body, the men of the forlorn hope were unable to retreat until nightfall.