One learns fast in a fight, and I marched this platoon and my next two troops in column through the jungle without any attempt to deploy until we got on the firing line.

This sounds simple.

But it was not.

I did not know when I had gotten on the firing line! I could hear a good deal of firing, some over to my right at a good distance, and the rest to the left and ahead.

I pushed on, expecting to strike the enemy somewhere between.
Soon we came to the brink of a deep valley.