The Battle of Tannenberg in World War I, was one of the most important battles of the Eastern Front. It was fought between Germany and Russia and had a considerable impact on Russia, since it is considered to be a massive defeat for the Russian Army.​

The Hundred Days Offensive of World War I was one of the last major conflicts of the First World War. In fact, the Allied victories during the Hundred Days Offensive eventually resulted in the end of World War I.

The Balkan Powder Keg of World War I was an important concept in relation to the nationalistic tensions that contributed to the outbreak of the war.

The Balkan Crisis before World War I was primarily driven by growing nationalistic tensions in the nations that make up the Balkans of southeastern Europe. Historians consider the crisis in the Balkans as an important cause of World War I.

Nationalism was one of the M.A.I.N. causes of World War I alongside militarism, alliance systems, and imperialism. It played an important role in Europe in the 19th and 20th centuries and helped set the stage for conflict between different nations.

Imperialism was one of the M.A.I.N. causes of World War I, alongside militarism, alliance systems and nationalism. For instance, events such as the Scramble for Africa played an important role in the outbreak of World War I.

The Naval Race before World War I was between Britain and Germany. The two nations competed to build up the most ships and control the seas around Europe. The Naval Race before World War I was important because it contributed to the outbreak of the war.

The dreadnought of World War I was an important battleship that was first developed by Britain and later copied by other countries. For instance, Germany famously modelled its own battleships after the British HMS Dreadnought.

Militarism was one of the main causes of World War I. In fact, the buildup of weapons, soldiers and ships before World War I was a major cause of the conflict.

Pan-Slavism in World War I was an important factor to the overall outbreak of the First World War. It was especially significant in relation to the July Crisis of 1914.