"The Brits used cordite a lot in their shells."
Not as a primary explosive; cordite is actually a pretty poor primary explosive.
D'Oh! Mike's right. Cordite was a propellant, not a primary explosive.
It looked like dried spaghetti noodles
cut to fit the casing:
Second one in from the right.
The overwhelming favorite in most WW1 artillery shells (the explosive filling, not the propellant) was lyddite, also known as picric acid. See
http://en.wikipedia.org/wiki/Lyddite for details.
This was a fairly unstable explosive, and was gradually replaced by amatol and TNT over time - but for most of WW1, it dominated.
Preacherman,
As I read Winston's post my first thought was "I bet Wikipedia would be the place to look..."