More on the events of January 16th...:

In a letter home to his mother, Owen wrote:

I can see no excuse for deceiving you about these last 4 days. I have suffered seventh hell.
I have not been at the front.
I have been in front of it.
I held an advanced post, that is, a ‘dug-out’ in the middle of No Man's Land. 

We had a march of 3 miles over shelled road then nearly 3 along a flooded trench. After that we came to where the trenches had been blown flat out and had to go over the top. It was of course dark, too dark, and the ground was not mud, not sloppy mud, but an octopus of sucking clay, 3, 4, and 5 feet deep, relieved only by craters full of water. Men have been known to drown in them. Many stuck in the mud & only got out by leaving their waders, equipment and in some cases their clothes.

High explosives were dropping all around and machine guns spluttered every few minutes. But it was so dark that even the German flares did not reveal us. 

My dug-out held 25 men tight packed. Water filled it to a depth of 1 or 2 feet, leaving say 4 feet of air.

One entrance had been blown in & blocked.
So far, the other remained.
The Germans knew we were staying there and decided we shouldn't.
Those fifty hours were the agony of my happy life.
I nearly broke down and let myself drown in the water that was now slowly rising over my knees. 

In the Platoon on my left the sentries over the dug-out were blown to nothing. One of these poor fellows was my first servant whom I rejected. If I had kept him he would have lived, for [officers'] servants don't do Sentry Duty.