What does "DLY" designate in relation to mortar fuses?

The designation "DLY" in relation to mortar fuses stands for "Delay." This indicates that the fuse is designed to ignite after a predetermined delay upon impact with a target. The purpose of a delayed fuse is to allow the projectile to penetrate into the target before detonation, maximizing the effect of the blast and ensuring that the explosive energy is best utilized against the target. This feature is particularly useful in targeting fortifications or areas where penetration is critical for achieving the desired effect.

In contrast, other fuse designations such as "Impact," "Superquick," and "Proximity" refer to different mechanisms of detonation. An impact fuse detonates the moment it strikes an object, while a superquick fuse is designed to detonate almost instantaneously, and a proximity fuse will trigger when it comes near a target, typically without direct contact. The key distinction of the DLY fuse lies in its timing mechanism that allows for that crucial moment of delay before explosion, making it essential for specific tactical applications.