On June 28, 1914, the assassination of Archduke Ferdinand and his wife Sophia was the spark that ignited Eastern Europe and World War I.
By the end of 1914, Austria had declared war on Serbia, Germany had declared war on Russia and France, Great Britain declared war on Germany, and Turkey joined forces with Germany.
By the end of 1915, Germany sunk the Lusitania and Italy declared war against Germany and Austria.
In February 1917, Germany launches unrestricted submarine warfare against any and all ships.
On April 6, 1917, America declares war on Germany and enters World War I.
In October 1917, the Italian Army suffered a major defeat at the Battle of Caporetto.
In early November 1917, Great Britain launched a major offensive on the Western Front of the War in Europe.
On November 20, 1917, British tanks advance and claim victory at Cambrai, France.
On December 5, 1917, Germany and Russia signed an armistice agreement.
In January 1918, US President Woodrow Wilson laid out a Fourteen Point peace plan.
On March 3, 1918, Russia and Germany formalize the Brest-Litovsk treaty.
On March 21, 1918, Germany launches its Spring Offensive against Allied forces in Europe and break through Allied lines on the Somme.
In April 1918, Germany launches an offensive in Flanders against the British 2nd Army. By the end of the month, Germany suffers 330,000 casualties.
On April 21, 1918, Germany’s infamous Red Baron (Manfred von Richthofen) is shot down and killed by the British. Even though Richthofen was an enemy combatant credited with 80 Allied kills, the British buried him with military honors.
By the end of May 1918, Germany launches another major offensive with the intension of slowing down the Allied forces in central France. At the same time, the US 1st Infantry Division captures Cantigny from the Germans. US General John Pershing decides to keep command of the 650,000 us troops in France instead of dividing them up with the British and French.
On June 6, 1918, US 2nd Infantry Division engage the Germans at the Battle of Belleau Wood and suffered their worst single loss to date of the war, with 5,000 American troops killed.
On June 9, 1918, Germany launches their 4th major offensive against the Allied forces.
On June 15, 1918, Austria launches an offensive against Italy. The Italian Army suffers 150,000 casualties and retreats. Austrian troops follow with many of them deserting.
In June and July 1918, a strain of influenza spreads around the world and hits troops on all sides of the war. Lasting about a year, the flu kills approximately 20 million people worldwide.
On this day, July 15, 1918, Germany launches its last major offensive of World War I. Known as the Second Battle of the Marne or the Marne-Reims Offensive, the Germans divide 52 divisions to launch a two prong offensive on Reims, France. Allied forces had anticipated the offensive and the French forces stopped the German attack from the east. On the west side of Reims, the US 3rd Infantry Division stopped the German offensive.
On July 18, 1918, American and French forces launch counter offensives against the Germans along the Marne.
On August 8, 1918, the British 4th Army soundly defeat German troops in the Somme, taking 13,000 prisoners. The battle was later described as the ‘Black Day of the German Army.’
From August to October 1918, Allied forces continue to drive back German troops on the Western and Eastern Fronts, taking thousands of prisoners.
On October 4, 1918, Germany sends a message, via the neutral Swiss, to President Woodrow Wilson, requesting discussions on peace. Negotiations and fighting continue, with Germany losing more ground and troops every day.
On November 11, 1918, Germany signs the Armistice, officially ending World War 1.
Sources for the above includes: World War I: 1918: A Fateful Ending; Second Battle of the Marne Begins with Final German Offensive; The Second Battle of the Marne, 1918; Second Battle of the Marne; Second Battle of the Marne; When the Americans Turned the Tide; World War I: Second Battle of the Marne; Timeline of World War One; Today, June 28, 1914: The Spark That Ignited World War I