Transcription:

Dear Jim
I am enclosing a codicil for a will I made a few years ago. I have just arrived and am in a hurry to get it off before going up to the trench in the morning and from the latest news on arriving I want to get it off my hands. If anything happens I should like you to see that the little that has to be fixed up is done. I had to make the codicil out in a hurry, but it conveys my wishes as nearly as I could arrange them in the hurry of the moment. I don’t expect to get a chance of writing for a few days. Feeling very tired
With love to you all
Yours affectionately
Harry