When the United States declared war on Spain in 1898, Lieutenant Colonel Arthur Lockwood Wagner was one of its army's best-known soldiers. The objective of Wagner's report was not only to point out what went right in Cuba, but also to note what went wrong and why, in order to perfect American combat techniques and safeguard American lives in wars. Wagner's argument was simple: if the army was to prevail in modern war, it would have to abandon its prejudices in the interest of combat effectiveness. The report that emerged was the first of its kind in the army's history, and led directly to the establishment of the modern doctrine known as lesson-learning. Wagner's critique of the Santiago campaign was consistent with his professional insistence that military history be combed for its lessons. Wagner had demonstrated only their theoretical validity, and it was to be determined if they were as well suited to the US Army as to Prussia's.