In May 1915, the Central Powers launched one of the greatest offensive operations of the First World War. The armies of Germany and Austria-Hungary planned to smash their way through Russia lines and tip the strategic balance in their favor. The result was one of the biggest and bloodiest campaigns of the war, known today as the Great Russian Retreat.

In the last years of the 19th century, tension was building in the Caribbean. American newspapers were filled with grisly reports of Spanish atrocities against the people of Cuba struggling for independence. US businessmen and expansionist politicians also saw practical opportunities in Spain’s struggles: great power status and an empire for the United States. It’s the Spanish-American War.

In early 1917, the United States was still neutral in the First World War. Meanwhile, German leaders were getting desperate – if they couldn’t find a way to break the war of attrition on the Western Front, the Allies would probably defeat them. The result was multiple gambles that staked everything on a quick victory with the risk of drawing the US into the war.

By April 1915, the Western Front was mired in trench warfare. Germany’s new Chief of Staff, General Erich von Falkenhayn, didn’t think his army could break the deadlock, and Germany needed to help struggling Austro-Hungarian forces in the East. Before the Germans turned against Russia though, they decided to attack in the West to keep the Allies off balance. They chose to strike at the vulnerable Ypres Salient – and they would support the coming offensive with a weapon their enemies had never seen.