While it's origins as a tactic is based with the evolution of Warplanes (in particular during World War I), the practice of “Dive Bombing” is the use of external Bombs electrically or manually released - at a target. The release of the Bomb (which was not Radar or Wire Guided), was increased in velocity and aim by the angle of the Aircraft releasing it. To accomplish this, an Aircraft needed to reach a specific altitude upon which it would radically change it's angle in a downward position. Upon reaching optimal positioning, the Aircraft would release it's Bomb. The Device would travel at this angle until it reached it's impact point (detonation). Most such Devices were timed (Fused) to detonate with both impact (Contact Detonation) or after penetration (through a Ship Deck). During World War II, various methods for Dive Bombing were experimented with. In a variant, Torpedo Planes (Aircraft designed to release Naval Ordnance), were able to travel to heights of 500-feet above water and “Snap Release” their Device. The Weapon would thus travel to it's target, much as a regularly launched Torpedo. The Japanese became masters of Dive Bombing Tactics in the 1930s and into the 1940s. Much of their techniques were copied and later modified by The US Navy. The advent of Dive Bombing Tactics were such as it spurred the advance of Aircraft specifically designed for this function. However, the advance of Rocket and Missile technology was as such that The Dive Bombing Tactic quickly became obsolete by the mid-1950s. Although obsolete, Dive Bombing “Theory” is still taught today by some World Navies.