Christmas 1916 found America walking a tightrope of neutrality as the World endured the third year of the Great War. While the Assassination of Austrian Archduke Franz Ferdinand and his wife Sophie in June 1914 precipitated the global conflict, the roots of the war lay in a longstanding system of interlocking alliances and lethal gamesmanship. While war in Western Europe may seem unthinkable today, people speaking German and people speaking French (and people speaking English) had been shooting at each other pretty much since there were people speaking German and French (and English).
So in the summer of 1914, Austria-Hungary declared war on Serbia. Czarist Russia came in on the side of Serbia. Germany then mobilized against Russia while demanding France stay out of the conflict despite treaty obligations (hoping to avoid a two-front war). Germany then attacked Luxembourg and declared war on France when Belgium refused to permit German troops to cross its borders. The UK then declared war on Germany in response to the incursion into Belgium. And the dominoes fell and Europe got is Great War.
So two entangled alliances took the field. Germany and Austria-Hungary were the core of the Central Powers, supported by the Ottoman Empire (reduced after the war to the modern nation of Turkey). The Allied Powers began with Russia, France and the British Empire, along with Serbia, Montenegro, and Belgium. Japan and Italy even allied with the Allies in the First World War.
On the Western Front, the German and French armies dug into trench warfare across Belgium and France—the Battle of Verdun lasted from February to December 1916, with 700,000 to 1,000,000 casualties in total. The British Army joined the French on the offense in the Battle of the Somme from July to November 1916. The Brits lost 420,000 casualties in the Somme, the French 200,000 and the German an estimated 500,000. In December 1914, in the first year of the war, regular soldiers from both sides took up the spontaneous Christmas truce, putting down their guns for pick-up games of soccer and share good will. The holiday truce was not to recur again.
On the Eastern Front, Russia quickly attacked Austrian Galicia and East Prussia at the start of hostilities, but were driven back and lost Warsaw in 1915. In November 1916, Germany and Austria re-created the Kingdom of Poland from formerly Russian territory as a puppet state. Dissatisfaction with the war grew in Russia as Tsar Nicholas led from the Austrian front, leaving governance to Empress Alexandra and the now infamous Grigori Rasputin, until his assassination at the end of December 1916. Revolution was coming to Russia in the New Year, which would collapse the Eastern Front, but this was not a foregone conclusion at Christmas time.
In the Balkans, Austria-Hungary and Serbia, and their allies, attacked and counter-attacked. Bulgaria declared war on Serbia, while Romania later came in for the Allies. In Greece. the pro-German King Constantine and Franco-Britsh forces contended for control before the King abdicated. Meanwhile, Italy, which had been allied with Germany and Austria-Hungary, had secretly allied with France with an eye on gaining territory on the Dalmatian coast. In May 1915, Italy declared war on Germany but suffered from poor strategies and tactics in the mountainous terrain. From April 1915 to January 1916, Britain, France and Russia engaged the Ottomans in the ill-fated Gallipoli Campaign, causing about 250,000 casualties on each side. Winston Churchill, veteran of India and the Boer Wars, served in the British Admiralty at the beginning of the war but resigned after the Gallipoli campaign, going on to serve on the Western Front.
The United States of America stood on the sidelines through all this, for the most part. However, on the high seas German cruisers and the British Royal Navy systematically hunted each other and each others merchant ships. In 1915, German U-boats sunk the passenger ship RMS Lusitania without warning, sending 1,198 passengers and crew to a watery grave, leading to widespread condemnation from neutral nations as a breach of international law. Sinking the Lusitania, on top of the 1914 Rape of Belgium, seemed to have broken American opinion in favor of war, despite equally wide-spread isolationism in the U.S. leading up to the Presidential election of 1916.
Looking back a century later, it might seem obvious that America would get sucked into the Great War. The Central Powers and Allies had extended their battle fronts from Europe across the Middle East, Africa and the Orient. Unrestricted naval and submarine warfare put Americans and American merchants in very real danger everywhere. But at the time, the Great War had not hit the homeland. While Pancho Villa had crossed the Mexican border, at Christmas 1916 we were still weeks away from the devastating Zimmermann telegram. At Christmas 1916, it was still THEIR war. It was soon to become OUR war.