After solving the gas machine puzzle and climbing to the surface, head left up the hill and command the dog to dig up this item.
"21 April 1915
We are in Belgium, a truly flat land that reminds me of our Winnipeg plains. The big difference is that it's so damp here, which makes the cold even colder. The guys and I are going to make you proud of us. The Canadians will be the big heroes of this war.
I'll write again soon,