The Triumph model H was used during WW1, 30,000 were produced for the army and by and large they worked well gaining the nickname "Trusty Triumph". However the girder fork spring, pointing forward and working against a yoke, took a lot of abuse. On the rough roads and off road, the yoke was known to fail, causing the fork to collapse forward almost certainly resulting in a crash. The DRs soon learned to put a strong leather strap around the fork in order to avoid this eventuality. Somewhere I've seen a picture of a bike with collapsed fork, I've given up trying to find it. If someone finds that picture, I'll add it to the post.
Below, not that clear but the safety strap is in place.