Leather doesn't last as long when it's constantly damp. Even when polished each night, mold blooms across its surface, dulling the shine and eating away at its strength.
Metal suffers a different, but not dissimilar fate. Rust eats away from the inside out, bubbling through and flaking away unprotected areas. Joints stiffen if not oiled constantly.
Preserve your weapons and armor, soldiers! When possible, hang your gear above the sodden ground. As you must breathe, so must they, for they will prove your only protection against the enemies known and unknown against whom we are set.
SIGNED: The Office of the Quartermaster