In case you missed it, two days ago was the 100th anniversary of the assassination of Archduke Franz Ferdinand. There was a low key ceremony in Sarajevo, and there are events planned all summer to commemorate the various actions that led to the outbreak of the war. I understand the Battle of Mons is going to have a particularly large remembrance.
Were you ever confused about the sequence of events that led from a small, localized dispute in the Balkans to a European-wide war? Unlike the relatively simple explanation of WWII (ie, Third Reich invades Poland) WWI can't be explained in a in a quick two or three sentence summary. So, I enjoyed this video from the BBC that nicely summarizes how all the Great Powers got sucked into a tiff between Austria-Hungary and Serbia... in the form of a rap battle between Princip, Franz Joseph I, Nicholas II, Wilhelm II, George V and France's Gen. Joffre (who just sits in the background). My favorite lyric? From George V: "You're taking an enormous punt/ No wonder my homies, and your's too/ Think you're a massive... difficult chap".