On the 100th anniversary of the US entry to World War I, these vivid colorized photos bring the Great War to life

On July 28, 1914, a month after a Bosnian-Serb assassinated Austrian Archduke Franz Ferdinand on a street corner in Sarajevo, the Austro-Hungarian Empire declared war on Serbia, beginning World War I.

Three bloody years later, the $4 on the side of the Allies, declaring war on the Central Powers on April 6, 1917.

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A soldier and horse wear gas masks at the Canadian Army Veterinary Corps Headquarters.

World War I saw a number of military innovations, including the use of planes, tanks, and chemical weapons. An armistice on November 11, 1918, was followed by the Treaty of Versailles, $4, on June 28, 1919.

Here are a few colorized photographs published by $4 showing life during World War I.

$4 and $4 composed an$4 of this post.