The answer is : The Civil War Era
The most important was The Battle of the Somme (1 July - 18 November 1916) was a joint operation between British and French forces intended to achieve a decisive victory over the Germans on the Western Front. For many in Britain, the resulting battle remains the most painful and infamous episode of the First World War The AEF helped the French Army on the Western Front during the Aisne Offensive (at the Battle of Château-Thierry and Battle of Belleau Wood) in the summer of 1918, and fought its major actions in the Battle of Saint-Mihiel and the Meuse-Argonne Offensive in the latter part of 1918.
New inventions!
I'm not sure if I'm correct for this one, correct me if I'm wrong.
Mark Twain & Ex- President Grover Cleveland.
