On 28 June, Secretary Stanton sent a message along to Daniel E Somes, the former US State Representative from Maine who had remained in Washington, DC after his term ended in 1861, requesting that he speak to the 25th and 27th Maine regiments about extending their stay "until the present emergency passes over". At 10:00 PM the following night, Mr. Somes met at Col. Wentworth's quarters to discuss this offer. The colonel summoned his captains in for a conference, and all were in agreement of what was asked of them by the President.
June 28, 1863.
Hon D E Somes,
I am directed by the President to say that he very much desires the Maine Regiments whose term of service is about expiring to remain in the service a short time until the present emergency passes over.
They will render aid of great importance to the Union which will properly be acknowledged by the Government.
You are authorized & requested to present the matter to the regiments in hope that their patriotic feelings will induce them to remain a short time. Yours truly
(signed) Edwin M Stanton
Secretary of War.
On Wednesday, 1 July 1863, Col Wentworth and his volunteers reported to Brig Gen'l DeRussey, who was commanding the defenses around Washington, at his headquarters in the Arlington House. Where they encamped for the next three days is unknown, but was somewhere along the Arlington Heights.
On the afternoon of Saturday, the 4th, the results of the Battle of Gettysburg were announced, and the order received to march for Washington. That evening, the train left for Portland, Maine. They arrived there on the 6th, and went back into camp. They would be mustered out over a week later, on the 17th of July.
It was not until the following Sept that Secretary Stanton began the process of preparing the medals for the 27th Maine men. E. D. Townsend, the Ass't Adjutant General, instead of procuring a list of the 300 volunteers who actually stayed behind, had created one from the muster out rolls, a list containing 864 men! He sent it along to clerk John Potts of the War Dep't, who sent it to Wm Wilson & Son, the manufacturers of the medal.
On 26 Jan 1865, the office of the Adjutant General sent the medals to Gov. Cony of Maine. He wrote to Mark Wentworth on the 30th, inquiring what all the medals were about. The colonel replied on Feb 2nd, explaining the situation, and asked the governor to forward them to Kittery, and he would take charge in distributing them to his former soldiers.
312 (pages from the History of the Twenty-Seventh Maine)
Medal of Honor List (comparing the 312 list with the 299 one)
Blog: A Medal Found (One of the undistributed medals found on a Wells beach)
On Family Search: a checklist, from the Maine State Archives, likely the one Wentworth used in distributing the medals to the volunteers: the 299 list