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United States Department of Defense United States Department of Defense

World War I

100th Anniversary

The assassination on June 28, 1914, of Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, would spark World War I. The Defense Department salutes the courage of the U.S. soldiers who fought for freedom's sake.


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Portrait photos of Gavrilo Princip and Archduke Franz Ferdinand.

JUNE 28, 1914

Bosnian-Serb activist Gavrilo Princip assassinated Archduke Franz Ferdinand, heir to the Austro-Hungarian throne.
Map of the first invasion of Serbia.

JULY 28, 1914

Austria-Hungary declared war on Serbia.
Serbian infantry positioned at Ada Ciganlija.

AUGUST 1, 1914

Germany, Austria-Hungary's strongest ally, declares war on Russia, Serbia's closest ally.
Photo of German soldiers in a railway goods wagon on the way to the front in 1914.

AUGUST 3, 1914

Germany declares war on France.
Map of the battle of Frontiers

AUGUST 7 - September 13, 1914

In the Battle of the Frontiers, Germany advanced into Belgium and France.
Photo of the Siberian Cer mountains

AUGUST 15-24, 1914

Battle of Cer was the first Allied victory.
Map of the battle of Tannenberg

AUGUST 26 - AUGUST 30, 1914

In the First Battle of Tannenberg, Germany defeated Russia as it moved westward.
Photo of German soldiers (wearing distinctive pickelhaube helmets with cloth covers) on the front at the First Battle of the Marne.

SEPTEMBER 5-12, 1914

In the First Battle of the Marne, French and British forces halted Germany's advance into France.
Photo of a German U-boat sinking a British ship.

FEBRUARY 4, 1915

Germany declared a war zone around the British Isles so that even neutral nations' vessels were subject to attack.
color map of the Allied forces.

APRIL 26, 1915

Italy joined Allied forces.
Ariel photo of German gas attack.

APRIL 22, 1915

Germany issued first large-scale chlorine gas attack, in violation of international treaties, against the French in the Second Battle of Ypres.
Map of the occupation of Poland in World War I.

MAY 5, 1915

Central Powers broke into Poland.
1915 painting of the sinking of Lusitania.

MAY 7, 1915

Germany sank the British Lusitania passenger ship, killing 1,198 of the 1,959 people on board. One hundred and twenty eight of the 197 Americans on board were killed. U.S. President Woodrow Wilson issued a warning to Germany, which led U.S. Secretary of State William Jennings Bryan, a firm neutralist, to resign.
Photo of German Cavalry entering Warsaw.

AUGUST 8, 1915

Germany captured Warsaw in "Great Advance" and caused Russia's "Great Retreat."
Portrait photo of Venustiano Carranza


U.S. recognized Venustiano Carranza as the new president of Mexico and fellow revolutionary Francisco "Pancho" Villa started a civil war with his raids across the country. Villa's raid into New Mexico killed 17 U.S. citizens and caused Wilson to send Gen. John J. Pershing in charge of a "The Punitive Expedition" to Mexico.
Photo showing horse wagons during the Serbian retreat.

NOVEMBER 9, 1915

Serbia fell to Austria-Hungary after being invaded by Slovenia, Croatia and Bosnia.
Portrait photo of Newton D. Baker.

MARCH 9, 1916

Newton D. Baker became the U.S. secretary of war. The former mayor of Cleveland had no military experience.
Photo of the HMS Warspite and HMS Malaya during the battle of Jutland.

MAY 31 - JUNE 11, 1916

The Battle of Jutland in the North Sea was the largest naval fight of the war with a full-scale clash of battleships. Like many WWI battles, there was no clear victor as it was considered a standoff whereby Britain asserted its control of the sea, but at huge costs in lives and ships.
Portrait photo of Rep. James Hay of Virginia, Chairman of the House Committee on Military Affairs.

JUNE 3, 1916

Congress passed the National Defense Act in response to American concern over military unpreparedness. The law appropriated money to expand the Army and Navy, allowed the National Guard to be called up for federal service, and created the Reserve Officer Training Corps.
Photo of World War I Russian infantry.

JUNE 4 - SEPTEMBER 20, 1916

In the Brusilov Offensive, Russian Gen. Aleksey Brusilov achieved victory by leading a surprise attack against the Austro-German line in two places.
Photo of soldiers of the Arab Army carrying their Flag.

JUNE 10, 1916

In the Battle of Mecca, an Arab revolt defeated the Ottoman Empire with Ottoman's surrender of Damascus.
Photo of British soldiers leaving their trenches in the Battle of the Somme.

JULY 1, 1916

Great Britain suffered 57,470 casualties and 19,240 dead at the Battle of the Somme.
Photo of Romanian Army officers in World War I.

AUGUST 28, 1916

Romania dropped its long-held neutrality and declared war on Germany and Austria-Hungary.
Two side-by-side photos of German Chancellor Theobald von Bethmann-Hollweg.

DECEMBER 12, 1916

Following a crushing defeat of Romania in the Battle of the Arges River, German Chancellor Theobald von Bethmann-Hollweg proposed a peace agreement that would have annexed portions of France and Belgium to Germany, which the Allies soundly rejected.
Photo of Falkenhayn's cavalry entering Bucuresti.

DECEMBER 18, 1916

President Wilson invited Allies and Central Powers to peace talks in which they were to state their "war aims." The talks collapsed when it became clear to the Central Powers that the U.S. was colluding with the Allies.
Photo of Woodrow Wilson and his cabinet in the Cabinet Room.

JANUARY 22, 1917

Wilson tried again at mediation with a suggestion of "peace without victory," which was accepted by the Allies and Austria-Hungary. Germany balked, however, and returned to a policy of unrestricted submarine warfare.
Photo of a newer Housatonic ship, similar to the one sunk in 1917.

FEBRUARY 3, 1917

Wilson severed diplomatic ties to Germany after it sank the US warship, the Housatonic.
Photo of Zimmerman's telegram decrypted and translated.

MARCH 3, 1917

British intelligence intercepted a telegram from German Foreign Minister Alfred Zimmermann to Mexico to join the war as Germany's ally against the U.S. with Japan as Mexico's ally. Zimmermann was attempting to delay U.S. entry into Europe and promised Mexico that Germany would help them win back Texas, Arizona and New Mexico.
Photo of General Maude's entry into Baghdad, 11 March 1917.

MARCH 11, 1917

Great Britain captured Baghdad.
Photo of one of Nicholas II, showing him at Tsarskoye Selo after his abdication in March 1917

MARCH 15, 1917

Internal unrest in Russia causes the abdication of Tsar Nicholas II in the start of the Russian Revolution.
Photo of President Wilson delivering his war message before Congress.

APRIL 6, 1917

Congress approved Wilson's request and declared war on Germany, becoming an "associated power," rather than a member, of the Allies.
Photo of a A Howitzer in the act of firing in the Battle of Messines Ridge.

JUNE 7-14, 1917

The Battle of Messines, at Ypres, caused 25,000 casualties for Germany and 17,000 for Britain after Britain successfully drove Germans from the area.
Photo of Captured British Mark IV tanks used by German troops.

JULY 15, 1917

The first successful allied offensive was The Second Battle of Marne when Germans attempted to encircle Reims.
Photo Australian gunners on a duckboard track in Ch√Ęteau Wood near Hooge, 29 October 1917.

AUGUST 22, 1917

Battles in Flanders and at Verdun caused more than a quarter of a million deaths.
Photo of Lenin speaking in Moscow.

OCTOBER 24, 1917

Vladimir Lenin and Leon Trotsky led the second phase of The Bolshevik Revolution that transformed Russia into a communist state.
A painting of the event.

NOVEMBER 5, 1917

A Supreme War Council of Allied forces was created at the Doullens conference.
Propaganda poster reads: 'Down with Bolshevism. Bolshevism brings war and destruction, hunger and death', anti-Bolshevik propaganda, Germany, 1919.

NOVEMBER 7, 1917

Vladimir Lenin and the Bolshevik Party assumed power in Russia.
Photo of officers from the staff of Field Marshall von Hindenburg meet the delegation of Soviet Russia.

DECEMBER 15, 1917

Russia surrendered to Germany and ceded Finland, Baltic provinces, parts of Poland and Ukraine to the Central Powers.
Map showing Armenia and Georgia.

FEBRUARY 24, 1918

Establishment of Democratic Republics of Armenia and Georgia.
Photo of German A7V tank in Roye, Somme, 21 March 1918.

MARCH 21, 1918

The Germans led a successful offensive on the Western Front known as Operation Michael, against the U.S., British and French near Amiens, France.
Photo of a collapsed building in Seicheprey, France 1918.

APRIL 20, 1918

The first major U.S. battle occurred at Seicheprey, along the Lys River near the Belgian-French border. It was a successful German attack that left 669 Americans dead or wounded, while fighting in support of the British.
Photo of the 1st Infantry Division entering Trier, Germany, November 1918.

MAY 28, 1918

U.S. Maj. Gen. Robert Lee Bullard launched the first U.S. offensive of the war at the French village of Cantigny, 60 miles north of Paris, at a heavily-fortified German observation point. The 1st Division, or "Big Red One," drove out the Germans over two days of fighting.
Photo of French troopers under General Gouraud, with their machine guns amongst the ruins of a church near the Marne, driving back the Germans.

JULY 20, 1918

U.S. and French forces drive out Germans from France's Marne River outside of Paris.
Painting of German prisoners of war being led towards Amiens.

AUGUST 8, 1918

The Start of 100 Days Offensive, British, French and Canadians advance into German territory in Battle of Amiens, taking more than 100,000 German soldiers prisoner and marking the beginning of the end for Germany.
Map of Bulgaria.

SEPTEMBER 29, 1918

Bulgaria surrendered to Allies.
Photo of German light cruiser Breslau after the Pursuit of Goeben and Breslau bombarded the Black Sea port of Theodosia.

OCTOBER 30, 1918

The Ottoman Empire surrendered to the Allies, Budapest, Prague and Zagreb declared independence and the Austro-Hungarian Empire fell.
Photo of the first page of the New York Times on November 11, 1918.

NOVEMBER 11, 1918

After suffering six million casualties, Germany signs an armistice with the Allies. Wilson demanded the abdication of the kaiser, ending imperial Germany, which was replaced with the democratic, Weimar Republic.
Painting of Dr Johannes Bell signing the Treaty of Versailles in the Hall of Mirrors, with the various Allied delegations sitting and standing in front of him.

JUNE 28, 1919

Signing of the Treaty of Versailles.

Centennial World War I Commemoration Effort Gears Up

In his day job, Robert J. Dalessandro is the director of the U.S. Army Center of Military History at Fort Lesley J. McNair here. He also is the acting chairman of the World War I Centennial Commission. Story

Nation Marks 100th Anniversary of World War I

"One day the great European War will come out of some damned foolish thing in the Balkans."

This prophecy, from German Chancellor Otto von Bismarck, came in 1888, and he was spot on. Story

World War I Facts »

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