The events and horrible human toll of WWI were commemorated in a poem by John McCrae:
We are the Dead. Short days ago
Take up our quarrel with the foe:
Or read up on WWI with one of these books:
The First World War: A Very Short Introduction. D521 H645 2008
Eleventh Month, Eleventh Day, Eleventh Hour: Armistice Day, 1918, World War I and its Violent Conclusion. D523 P44 2004
(and if you're wondering what the deal with the "red flower" is, check out the Poppy Appeal).