By the end of the military and civilian deaths for great britain topped one million, 1.7 million for france, 2.3 million for russia, and 2.5 million for germany.

World War I

Explanation:

The World War I (also known as The Great War) was an armed conflict among several nations mainly in Europe between 1914 and 1918. It all began when Archduke Franz Ferdinand of Austria was murdered in the city of Sarajevo. As a consequence, Autria-Hungary declared war on Serbia and caused many allies on both sides to confront.

During the war, the 2 main coalitions in Europe were comprised by the Triple Alliance(Germany, Italy and Austria-Hungary) and Triple Entente(Russia, France and Great Britain). They fought with all sort of weapons like rifles, granades, bombs, tanks, aircrafts and a very large amount of infantry.

It ended 4 years later with the surrender of the Triple Alliance and forced to sign the Treaty of Versailles. This war left 1 milion deaths in GB, 1.7 millions in France, 2.3 in Russia, and 2.5 millions for Germany. There would no be a conflict of this magnitude for 20 years, when World War II began.