The Castle was the headquarters for American soldiers while rumour has it that Al Jolson played a show for them in the town hall during their stay.
The exhibition will be curated by Sam McCleary who has put out an appeal for memorabilia relating to this period in history.
He said: “We’re hoping to have it up and running by the end of March.
“We’re looking for anyone with any memorabilia about the Americans in Lurgan.
“Only last week we were given a letter from an American officer saying thank you for a tour of the waterworks.
“We’ve lots of bits and pieces of our own and I’m sure there’s people out there who have lots more fascinating pictures, documents and the like.”
He continued: “Brownlow House was the headquarters of the American forces.
“They were also based on the Lough Road at Kircassock House in Dromore and there was a military hospital at Waringsfield as you come into Moira.
“It’s even rumoured that Al Jolson sang in the town hall.
“There’s a rich history there which will make for a great permanent exhibition.”
Sam added: “Anyone who has anything they think would be of interest should contact me on 3832 2674.”
At the outbreak of WWI, Brownlow House was the headquarters of the 16th Battalion Royal Irish Rifles and the 10th Battalion Royal Irish Fusiliers, while in the second World War various contingents of British and American troops were stationed there. General Eisenhower, the Supreme Allied Commander, is said to have stayed at Brownlow House and the room he stayed in has since been re-named the Eisenhower room.