Canada fought on the side of Britain in World War I.

The Flying Tigers flew in France during World War I.

"The Red Baron" was the nickname of a Communist leader.

World War I began immediately after an Austrian nobleman was slapped in public.

There were many veterans of World War I alive in 2000.

Italy was an ally of Germany in World War I.

World War I ended on November 11, 1918.

The Triple Entente was an association between Great Britain, the United States, and France.

The treaties of Brest-Litovsk were signed by the Central Powers with the Ukrainian Republic and with Soviet Russia.

Joseph-Jacques-Césaire Joffre was known as “the Victor of the Marne.”

The Germans first used poison gas as a weapon during the Battle of Passchendaele.

The Fourteen Points outlined Woodrow Wilson's proposals for a postwar peace settlement.

The sinking of the Lusitania by a German U-boat in May 1915 prompted the United States' immediate entry into World War I before the end of the year.

William Barker became the most-decorated war hero in Canadian history as a fighter pilot in World War I.

The Hindenburg Line was a defensive barrier improvised by the French Army on the Western Front in World War I.

"Big Bertha" was a term for a type of howitzer that was first used by the German army during World War I.

The Balfour Declaration was a statement of British support for “the establishment in Palestine of a national home for the Jewish people.”

Sir Ian Hamilton led the Mediterranean Expeditionary Force in the unsuccessful campaign against Turkey in the Gallipoli Peninsula.

Aleksey Alekseyevich Brusilov led the largest Russian assault during World War I.

The Triple Alliance was a secret agreement between Germany, Austria-Hungary, and the Ottoman Empire.

The Treaty of London was a secret treaty to bring Italy into World War I.

Blimps were used by navies during World War I.

The Battle of Verdun was the shortest battle of World War I.

Raymond Poincaré was president of the French Third Republic during World War I.

The Sykes-Picot Agreement was a secret convention made during World War I between Great Britain and the United States.

The Paris Peace Conference set the peace terms after World War I.

The Battles of the Isonzo comprised five battles fought during World War I.

The Constantinople Agreement was a secret agreement between the members of the Triple Entente.

The French general Philippe Pétain became a national hero for his victory at the Battle of Jutland.

The Treaty of Versailles was a peace document signed by the Allied powers and by Germany at the end of World War I.

The Battle of the Frontiers is the collective name for the first great clashes on the Western Front of World War I.

The Treaty of Sèvres abolished the Austro-Hungarian Empire.

The Battle of Tannenberg ended in a German victory over the Russians.

Edmund Henry Hynman Allenby, 1st Viscount Allenby, directed the Palestine campaign in World War I.

The Treaty of Lausanne was the final treaty concluding World War I.

Paris Guns were a type of long-range cannon used by the French during World War I.

The first depth charges, or depth bombs, were developed by the United States during World War I.

The Dawes Plan was the arrangement for payments of reparations by Germany after World War I.

The Second Battle of the Marne was the first large German offensive of World War I.

The Battle of Caporetto is also known as the 12th Battle of the Isonzo.

The United States declared war on Germany in 1916.

The Black Hand was a secret Serbian society that helped plan the assassination of Franz Ferdinand, precipitating the outbreak of World War I.

The British Expeditionary Force went to France at the start of both World War I and World War II to support French armies.

The Battle of Amiens marked the beginning of the "hundred days," a string of Allied offensive successes that led to the end of the war.

The Maxim machine gun was largely responsible for the epithet “the machine gun war” for World War I.

The Battle of Arras was a German offensive on French defenses.

Alvin York was an American World War I hero.

The battles of the Meuse-Argonne were a series of final confrontations on the Western Front in World War I.

Isaac Newton Lewis is best known for his invention of the Hotchkiss machine gun, widely used in World War I.

The observance of Veterans Day in the United States originated on the first anniversary of the 1918 armistice that ended World War I.

Italian Prime Minister Vittorio Orlando headed Italy’s delegation to the Versailles Peace Conference.

The Christmas Truce of 1914 had been officially agreed upon in early December after an appeal by Pope Benedict XV.