[1] Greene, college educated and obsessed with the military and technology, designed and patented many rifles.

On 23 July 1860, Greene joined the 5th Massachusetts Militia Regiment, being its Lieutenant Colonel when the civil war began.

During the Battle of Gettysburg, Greene commanded the unit during heavy fighting in the Wheatfield, where the regiment lost 25 killed and 125 wounded.

Following the Battle of Chickamauga, on September 20, 1863, Greene was promoted to full colonel and transferred to the 6th US Infantry.

On 13 April 1865, Colonel James D. Greene was promoted to Brevet Brigadier General.