Per the History Channel:
On its 100th anniversary, The Great Martian War tells the story of the catastrophic events and unimaginable horrors of 1913-17, when Humankind was pitted against a savage Alien invasion.
With powerful and detailed First World War parallels, The Great Martian War fuses sci-fi fantasy with specialist factual history to explore the real-world tragedies and unique horror of World War One.
Combining period archive with state-of-the-art special effects and featuring moving interviews with aging veterans, the show takes in the entire sweep of the conflict: from the devastation of Western Europe where a rag-tag alliance digs in against monstrous Alien war-machines unaware that deep flaws exist in their Generals’ central strategy, to the political battle for the Whitehouse where President Wilson struggles to maintain US Neutrality; from the skies of central London where allied bi-planes do spectacular battle with a towering Alien Tripod, to the War’s catastrophic final act in which the Allies, standing on the brink of total defeat, must decide if launching an untested and potentially devastating secret weapon is worth risking the lives of millions of men in the field and a global pandemic.
Here's an IMDB summary:
Documentary-drama recounting the Martian War of 1913 - 1917. Europe was on tenterhooks in the 2nd decade of the 20th century, everyone was expecting a Great War between the major European powers. But then, in 1913, something crashed into the forests of SW Germany. Troops were sent to investigate but were wiped out. Martian fighting machines began making their way across Western Europe and the countries of Europe combined forces to resist them.
With aspects taken from The War of the Worlds (movie version here) by H.G. Wells and from WWI itself, this dramatisation presents a documentary style look at events as they unfolded and the effect they had of our world today. Lots of references to real events including the mass attacks and defeats as men were thrown against machines on the Western front, the Christmas truce and the Angel of Mons, America's isolationism and late entry into the conflict, the worldwide "Spanish" flu epidemic that killed more people than the war, and many other things.
It's not perfectly clear, but this seems to be based on a now out-of-print book from a few years ago called The Martian War: A Thrilling Eyewitness Account of the Recent Invasion As Reported by Mr. H.G. Wells.
Lots more at History Channel, via Kuriositas.