The Vickers Tank Periscope MK.IV, invented by Polish

Poles

thumb|right|180px|The state flag of [[Poland]] as used by Polish government and diplomatic authoritiesThe Polish people, or Poles , are a nation indigenous to Poland. They are united by the Polish language, which belongs to the historical Lechitic subgroup of West Slavic languages of Central Europe...

 engineer Rudolf Gundlach

Rudolf Gundlach

Rudolf Gundlach was a Polish engineer, inventor and tank designer. He headed the design division of the Armored Weapons Development Office .He was the chief designer of the Ursus wz...

, was first patented in 1936 as Gundlach Peryskop obrotowy. It was the first device to allow the tank

Tank

A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 commander to have a 360-degree view from his 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.

The design was first used in the Polish 7-TP light tank. Shortly before the war it was given to the British

British Army

The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 and was used in most tanks of WWII

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, including the British Crusader

Crusader tank

The Tank, Cruiser, Mk VI or A15 Crusader was one of the primary British cruiser tanks of the early part Second World War and perhaps the most important British tank of the North African Campaign...

, Churchill

Churchill tank

The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...

, Valentine

Valentine tank

The Tank, Infantry, Mk III, Valentine was an infantry tank produced in the United Kingdom during the Second World War. More than 8,000 of the type were produced in 11 different marks plus various purpose-built variants, accounting for approximately a quarter of wartime British tank production...

, and Cromwell

Cromwell tank

Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...

and the American

United States Army

The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 Sherman

M4 Sherman

The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...

. The design was later copied and used extensively in tanks of the USSR

Red Army

The Workers' and Peasants' Red Army started out as the Soviet Union's revolutionary communist combat groups during the Russian Civil War of 1918-1922. It grew into the national army of the Soviet Union. By the 1930s the Red Army was among the largest armies in history.The "Red Army" name refers to...

 (including the T-34

T-34

The T-34 was a Soviet medium tank produced from 1940 to 1958. Although its armour and armament were surpassed by later tanks of the era, it has been often credited as the most effective, efficient and influential design of World War II...

 and T-70

T-70

The T-70 was a light tank used by the Red Army during World War II, replacing both the T-60 scout tank for reconnaissance and the T-50 light infantry tank for infantry support. The T-80 light tank was a more advanced version of the T-70 with a two-man turret—it was only produced in very small...

) and Germany

Wehrmacht

The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...

.

It was first implemented in TKS and 7TP Polish tanks. As a part of Polish-British pre-war military cooperation, patent was sold to Vickers-Armstrong. It was produced as Vickers Tank Periscope MK.IV (pictured), and build into all British tanks (Crusader, Churchill, Valentine, Cromwell). After fall of Poland, Germany, USSR and Romania captured some equipment, allowing them to copy the invention. In USSR 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) and implemented in all tanks (including the T-34 and T-70). All Axis tanks and APC (including tanks of Italy, Romania, Hungary, Finland and Japan) were equipped or retro-fitted with this periscope till 1941. Later technology was transferred to USA and as a periscope M6 implemented in all US tanks (M3/M5 Stuart, M4 Sherman and others). In the end of WWII technology was adopted throughout the world.