Editing Vickers Tank Periscope MK.IV

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[[Image:Gundlach periscope.jpg|thumb|upright|Gundlach periscope.]]
The '''Gundlach Periscope''', usually known under its British designation as '''Vickers Tank Periscope MK.IV''', was a revolutionary invention by Polish engineer [[Rudolf Gundlach]], manufactured for Polish [[7TP]] tanks from the end of 1935 and patented in 1936 as the ''Peryskop obrotowy Gundlacha''. It was the first device to allow the [[tank]] commander to have a 360-degree view from his [[gun turret|turret]] with a single periscope. By rotating the periscope and allowing the tank commander to look backwards through the second [[eyepiece]], he no longer had to change position to look behind the turret. Early tanks had small turrets and fixed seating, without an independently rotating cupola, and so the commander wasn't easily able to move himself to another rear-facing periscope.

On 14 June 1935 it was officially adopted by the [[Polish Army]], as reversible periscope G wz. 34.<ref>Mirosław Zientarzewski (in Polish), ''Peryskop odwracalny wz. 34'', "Militaria i Fakty" nr 2/2006 , p. 48</ref> The design was first used in the [[TKS]] [[tankette]], then in [[7TP]] light tank. Shortly before the war it was given to the [[United Kingdom|British]] and was used in almost all tanks of [[World War II|WWII]], including the British [[Crusader tank|Crusader]], [[Churchill tank|Churchill]], [[Valentine tank|Valentine]],  and [[Cromwell tank|Cromwell]] and the [[United States Army|American]] [[M4 Sherman]]. After the German and Soviet attack and fall of Poland in 1939 it was copied entirely from captured 7TP and TKS Polish tanks and later used by the [[USSR|Soviets]] for their tanks (including the [[T-34]] and [[T-70]]).

As a part of Polish-British pre-war military cooperation, the patent was sold for one [[Polish zloty|zloty]] to [[Vickers-Armstrong]]. It was produced as the Vickers Tank Periscope MK.IV (pictured), and built into all British tanks (Crusader, Churchill, Valentine, Cromwell). After the fall of Poland, Germany, USSR and Romania captured some equipment, allowing them to copy the invention. In USSR the Gundlach periscope was known as MK-4 (harking to the British designation, as Russian sources openly confirm that it was copied from samples acquired with British-supplied tanks)<ref>{{citation |title=T-34 Vs StuG III: Finland 1944 |first=Steven J. |last=Zaloga |publisher=Osprey |page=13}}</ref> and implemented in all tanks (including the T-34 and T-70). At the end of World War II this technology was adopted throughout the world and used basically unchanged for almost 50 years, until it was replaced by electronic devices.

== References ==
{{Reflist}}
* {{cite book |first1=Grzegorz |last1=Łukomski |first2=Rafał E. |last2=Stolarski |title=Nie tylko Enigma... Mjr Rudolf Gundlach (1892–1957) i jego wynalazek |trans-title=Not Only Enigma... Major Rudolf Gundlach (1892–1957) and His Invention |year=1999 |location=Warsaw-London |lang=pl |isbn=}}
* [http://www.freepatentsonline.com/2130006.pdf 1938 US patent 2130006 "periscope for armored vehicles"]

[[Category:Armoured fighting vehicle vision and sighting equipment]]
[[Category:History of the tank]]
[[Category:Military equipment of Poland]]
[[Category:Polish inventions]]