BBC documentary of WWI

The Great War(1964)
Part 1:

Strong intro.

http://en.wikipedia.org/wiki/The_Great_War_(documentary)

Big Bertha and the invasion of Belgium:
http://en.wikipedia.org/wiki/Big_Bertha_(howitzer)
http://en.wikipedia.org/wiki/German_invasion_of_Belgium

Paris Gun and the siege of Paris:
http://en.wikipedia.org/wiki/Paris_Gun