World War 1 isn't really my area of expertise. That is World War 2 but I do know enough about it to say that it was a horrific 4 year period in human history for all sides involved and I have much respect for all those who fought in the Great War for their countries.
World War 1 is on my list of things to learn more about. From what I do know the political situation before it started was fascinating.
I'd recommend Dan Carlin's Hardcore History podcast series on WW1 (Blueprint for Armageddon it's called). Think there were 5 podcasts - 1 for each year of the war, each one approx 4 hours long. Fascinating and horrific at the same time, while being very informative (though I think he sexes some things up for entertainment purposes).