Military history of Poland during World War II

In World War II, the Polish armed forces were the fourth largest Allied forces in Europe, after those of the Soviet Union, United States and Britain. Poles made substantial contributions to the Allied effort throughout the war, fighting on land, sea, and in the air.

Polish forces in the east, fighting alongside the Red army and under Soviet high command, took part in the Soviet offensives across Belarus and Ukraine into Poland and across the Vistula and Oder Rivers to the Battle of Berlin.

In the west, Polish paratroopers from the 1st Independent Polish Parachute Brigade fought in the Battle of Arnhem / Operation Market Garden; while ground troops were present in the North Africa Campaign (siege of Tobruk); the Italian campaign (including the capture of the monastery hill at the Battle of Monte Cassino); and in battles following the invasion of France (the battle of the Falaise pocket; and an armored division in the Western Allied invasion of Germany).

Particularly well-documented was the service of 145 Polish pilots flying British planes under British Command during the Battle of Britain, 79 in mixed squadrons under the RAF after July 1940, 32 in wholly Polish Squadron 303 after 31 August 1940 and 34 in entirely Polish Squadron 302. Other instances of service flying French planes in the Polish Air Force took place during the Battle of Britain at the same time, and from 1944 the Polish Air Force (also with British planes) was established in Britain.

Some Polish contributions were less visible, notably the prewar and wartime decrypting of German Enigma-machine ciphers by cryptologists Marian Rejewski, Henryk Zygalski, and Jerzy Różycki. An extensive Polish intelligence network also proved of great value to Allied intelligence.

The European Theatre of World War II opened with the German invasion of Poland on Friday September 1, 1939, followed by the Soviet invasion of Poland on September 17, 1939. On 6 October, following the Polish defeat at the Battle of Kock, German and Soviet forces gained full control over Poland. The success of the invasion marked the end of the Second Polish Republic, though Poland never formally surrendered. A Polish Underground State with a government-in-exile that would eventually set up headquarters in London resumed the struggle against the occupying powers. The Polish forces in the West, as well as in the East and an intelligence service were established outside of Poland, and contributed to the Allied effort throughout the war.

Invasion of Poland

The invasion of Polish Second Republic by the military forces of Nazi Germany on September 1, 1939, marked the beginning of World War II in Europe. The Soviets invaded Poland on September 17 as had been agreed with Nazi Germany in the Molotov-Ribbentrop Pact.

thumb|upright|left|Stalin and Ribbentrop shaking hands after the signing of the pact in the Kremlin

thumb|upright|left|Polish Army soldier showing last remaining part of destroyed German bomber [[Heinkel He 111 in Warsaw 1939.]]

In keeping with the terms of the Secret Additional Protocol of the Molotov–Ribbentrop Pact Germany informed the Soviet Union that its forces were nearing the Soviet interest zone in Poland and so urged the Soviet Union to move into its zone. The Soviets had been taken by surprise by the speed of the German advance as they had expected to have several weeks to prepare for an invasion rather than merely a few days. They did promise to move as quickly as possible.

Aid to Jews

thumb|Jewish prisoners liberated by Polish [[Home Army from German Gęsiówka camp in 1944 Warsaw Uprising]]

A substantial number of Poles risked their lives in the German occupation to save Jews. German-occupied Poland was the only European territory where the Germans punished any kind of help to Jews with death for the helper and his entire family. Even so, Poland was also the only German-occupied country to establish an organization specifically to aid Jews. Known by the cryptonym Żegota, it provided food, shelter, medical care, money, and false documents to Jews. Most of Żegota's funds came directly from the Polish Government-in-Exile in Great Britain.

Throughout the war the German state was forced to divert a substantial part of its military forces to keep control over Poland:

thumb|[[Henryk Dobrzański "Hubal"'s Detached Unit of the Polish Army – first partisan of World War II and his partisan unit – winter 1940]]

thumb|Captured German [[Panther tank – armored platoon of batalion Zośka under command of Wacław Micuta]]

thumb|Members of AK "Wiklina" entering [[Zamość 1944]]

thumb|[[w:pl:Cyprian Odorkiewicz|Cyprian Odorkiewicz commander of "Krybar" Regiment (second from left) inspects ammunition for PIAT anti-tank weapon belonging to "Rafałki" unit in the 1944 Warsaw Uprising]]

thumb|upright|1944 [[Warsaw Uprising – Patrol of Lieut. Stanisław Jankowski ("Agaton") from Batalion Pięść, 1 August 1944: "W-hour" (17:00)]]

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|+ <br /><small>(does not include annexed territories of Poland and parts of Kresy) The total number of those reports is estimated at 80,000, and 85% of them were deemed high or better quality. Despite Poland becoming occupied, the Polish intelligence network not only survived but grew rapidly, and near the end of the war had over 1,600 registered agents According to , for the Western Allies, the intelligence provided by the Home Army was considered to be the best source of information on the Eastern Front.

In a period of more than six and a half years, from late December 1932 to the outbreak of World War II, three mathematician-cryptologists (Marian Rejewski, Henryk Zygalski and Jerzy Różycki) at the Polish General Staff's Cipher Bureau in Warsaw had developed a number of techniques and devices including the "grill" method, Różycki's "clock", Rejewski's "cyclometer" and "card catalog", Zygalski's "perforated sheets", and Rejewski's "cryptologic bomb" (in Polish, "bomba, precursor to the later British "Bombe", named after its Polish predecessor) to facilitate decryption of messages produced on the German "Enigma" cipher machine. Just five weeks before the outbreak of World War II, on July 25, 1939, near Pyry in the Kabaty Woods south of Warsaw, Poland disclosed her achievements to France and the United Kingdom, which had, up to that time, failed in all their own efforts to crack the German military Enigma cipher.

thumb|[[Armia Krajowa and V-1 and V-2|Home Army intelligence report with V1 and V2 schematic drawings.]]

thumb|right|[[Armia Krajowa|Polish Home Army recovers a V-2 from the Bug River.]]

Polish Home Army (Armia Krajowa, AK) intelligence was vital to locating and destroying (18 August 1943) the German rocket facility at Peenemünde and to gathering information about Germany's V-1 flying bomb and V-2 rocket. The Home Army delivered to the United Kingdom key V-2 parts after a rocket, fired on 30 May 1944, crashed near a German test facility at Sarnaki on the Bug River and was recovered by the Home Army. On the night of 25–26 July 1944 the crucial parts were flown from occupied Poland to the United Kingdom in an RAF plane, along with detailed drawings of parts too large to fit in the plane (see Home Army and V1 and V2). Analysis of the German rocket became vital to improving Allied anti-V-2 defenses (see Operation Most III). The II Bureau is reported to have had two agents in the upper levels of the German high command.

The researchers who produced the first Polish-British in-depth monograph on Home Army intelligence (Intelligence Co-operation Between Poland and Great Britain During World War II: Report of the Anglo-Polish Historical Committee of 2005) and who described contributions of Polish intelligence to Allied victory as "disproportionally large" have also argued that "the work performed by Home Army intelligence undoubtedly supported the Allied armed effort much more effectively than subversive and guerilla activities."

Polish Forces (West)

Army

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|+Polish Armed Forces in the West <br />at the height of their power

These were mostly members of the German minority in Poland who were considered by the Nazi authorities to be ethnically German (Volksdeutsche). In 1939 in the Invasion of Poland they created the paramilitary organisation Volksdeutscher Selbstschutz, and actively supported German forces in occupied Poland.

On the Western Front, German military personnel of Polish ethnicity, held in prisoner-of-war camps, became a substantial source of manpower for the Polish Armed Forces in the West. Nearly 90,000 former German military personnel were eventually recruited into the Polish Armed Forces in the West. By Victory Day (9 May) in 1945, a third of Polish service members in the West were former members of the German Armed Forces. Initially it was mounted in Polish tanks such as the 7TP and TKS. Subsequently, the design patent was sold to the British for a nominal sum and used in most tanks of World War II, including the Soviet T-34, the British Crusader, Churchill, Valentine and Cromwell tanks, and the American M4 Sherman. The main advantage of the periscope was that the tank commander no longer had to turn his head in order to look backwards. The design was also later used extensively by the Germans.

pistolet wz. 35 Vis, often simply called the "Radom" in English sources, is a 9 mm caliber, single-action, semi-automatic pistol. It was adopted in 1935 as the standard handgun of the Polish Army. The design was appropriated by the Germans and from 1939 to 1945, 312,000–380,000 VIS pistols were produced and used by the German paratroopers and police as the 9 mm Pistole 35(p).
PZL.37 Łoś was a Polish twin-engine medium bomber designed in the mid-1930s at the PZL factory in Warsaw by Jerzy Dąbrowski, and used operationally in the Invasion of Poland in 1939. Thanks to the laminar-flow wing it was one of the most modern bombers in the world before World War II.
Swiatecki bomb slip, a bomb-release system was invented by Władysław Świątecki in 1925 and patented in the 1926 in Poland and abroad.

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