Editing Periscope (section)

===Periscopic gunsights===
Periscopic [[Sight (device)|sights]] were also introduced during the Second World War. In British use, the Vickers periscope was provided with sighting lines, enabling front and rear prisms to be directly aligned to gain an accurate direction.  On later tanks such as the Churchill and Cromwell, a similarly marked episcope provided a backup sighting mechanism aligned with a vane sight on the turret roof.

Later, US-built Sherman tanks and British [[Centurion tank|Centurion]] and [[Charioteer tank|Charioteer]] tanks replaced the main telescopic sight with a true periscopic sight in the primary role. The periscopic sight was linked to the gun itself, allowing elevation to be captured (rotation being fixed as part of rotating turret). The sights formed part of the overall periscope, providing the gunner with greater overall vision than previously possible with the telescopic sight. The [[Chieftain (tank)|FV4201 Chieftain]] used the TESS (Telescopic Sighting System) developed in the early 1980s that was later sold as surplus for use on the [[McDonnell Douglas Phantom in UK service|RAF Phantom]] aircraft.<ref>{{cite web | url=https://www.david-gledhill.co.uk/the-phantom/tess/ | title=TESS :: David Gledhill }}</ref><ref>{{cite web | url=https://bpag.co.uk/the-day-of-the-j/ | title=The Way of the J. – British Phantom Aviation Group }}</ref>