The more I clean, the more dirty I get Before the course, I am preset What am I?

A tiny book of you, dutifully keeping track of all of your wanderings. This book may be all about you, but it is a highly treasured key! Keep it secret, keep it safe, and all will be well.

An army travels on this, apocryphally according to Napoleon or Frederick the Great

Printed. Dyed. Under a tie. Cotton or poly. Full sleeved or shy. Remove just one letter, its profane in its cry. The upper half’s sheath. Some pocketed high.

I bend what’s straight so sight can crawl, Through metal halls with none at all. No windows here, yet crews still cope, What am I?