Infuriated by the German sinking of the liner Lusitania, the author (an American citizen) travels to England and enlists in the Royal Fusiliers, prior to America's entry into the war. This is a book about his "experiences in the language of Tommy sitting on the fire step of a front-line trench on the Western Front-just as he would tell his mate next him what was happening at a different part of the line." He was in the front-line trench of the Western Front.

It was the biggest bestseller of the war, selling a million hardcover copies. The best part may be its appendix, "Tommy's Dictionary of the Trenches," which is a dictionary of slang and other terms used by British soldiers.

A classic at the time by an American who fought in the British Army. Books of this sort were published as propaganda to tilt American public opinion towards the Allied cause.