The resignation of a monarch, either voluntarily or under duress. Several European monarchs abdicated during World War I, most notably Nicholas II of Russia in 1917.

An alliance is a formal agreement between two or more nations, pledging military, logistic or financial support to each other in the event of war or aggression. Military alliances are considered a piv [..]

The alliance system describes Europe’s diplomatic organisation before 1914 and its heavy reliance on alliances, supposedly as a deterrent to war.

Annexation is the forced acquisition of a region or territory by a more powerful state, such as Austria-Hungary’s annexation of Bosnia in 1908.

ANZAC is an acronym for the Australian and New Zealand Army Corps, a joint force assembled in early 1915 to participate in the Gallipoli campaign. ANZAC Day (April 25th) is a day of commemoration in b [..]

An arms race is a period where two or more nations engage in the rapid production of military technology and equipment, usually in response or rivalry to each other. The arms race and build up of mili [..]

An armistice is a temporary suspension of hostilities in a war, often while a peace treaty is being negotiated. The armistice that ended fighting in World War I was signed at dawn on November 11th 191 [..]

Artillery is a collective term for large calibre mobile guns, capable of firing explosive shells that cause considerable destruction. Artillery fire caused more deaths in World War I than any other fo [..]

Assassination is the murder of a monarch, political leader or other significant figure. Assassinations are usually designed to stimulate or trigger political change.

Autocracy is a system of government where all political power and sovereignty is vested in a single ruler, usually a king, tsar or emperor.