Five seconds after the fuse is lighted the grenade explodes.

It must be timed exactly.

If thrown too quickly the enemy is liable to pick it up and hurl it back in time to create the explosion in one's own lines.

No one cares to hold a grenade long after the fuse is lighted so the boys sometimes threw them ahead of the signal.
"Shorty" Childress of B company, 371st Infantry, had been drilled with dummy grenades.

When given the real thing he released the pin and immediately heard the fulminating fuse working its way down into the charge.