He was one of 69 children and the third-oldest son of Joseph Chandler (1725–1776) and his wife Lydia (née Eastman; 1726–1820).

However, he borrowed money from Dearborn and bought a farm near Monmouth in the District of Maine, then a part of Massachusetts.

On July 8, 1812, he resigned his militia office and was commissioned as a brigadier general of the United States Army.

[2] The first part of the war he was serving under Major General Henry Dearborn as the commander of one of three brigades of the Army of the North.

[6] At the beginning of June 1813 he accompanied Brigadier General William H. Winder during the Niagara campaign on an advance into Canada.

At the Battle of Stoney Creek Chandler was wounded, and both he and Winder were captured, when they wandered into the British line, thinking it was their own.

Chandler subsequently served defending the coast of New Hampshire and Maine, coordinating efforts between the local militia and federal units.

During his time in the Senate, Chandler was the chairman of the Committee on Militia during the 18th through 20th Congresses and played a key role in establishing the arsenal at Augusta, as well as the construction of the military road from Bangor to Houlton.