I'm just starting to read about this period, but out of the five or six books I've read the one I liked best was "The Dardanelles Campaign" by Henry Nevinson, published in 1919. There is a lot of detail and some fold-out maps in the back, including one 18"x18" with all the Allied trenches of the southern zone. IIRC, Nevinson was a staff officer there during some of the campaign, and also visited the sites afterwards.