Польша Коммунистік Партиясының Тарихы (Polsha Kommunistik Partiyasynyn Tarihy)

The interwar Communist Party of Poland (Komunistyczna Partia Polski, KPP) was a communist party active in Poland during the Second Polish Republic. It resulted from a December 1918 merger of the Social Democracy of the Kingdom of Poland and Lithuania (SDKPiL) and the Polish Socialist Party – Left (PPS – Left) into the Communist Workers' Party of Poland (Komunistyczna Partia Robotnicza Polski, KPRP). The Communist Party of Poland (until 1925 the Communist Workers' Party of Poland) was an organization of the radical Left. Following the ideas of Rosa Luxemburg, In March 1919, through its representative Józef Unszlicht, the KPRP took part in the founding of the Communist International (Comintern or the Third International) in Moscow.

The KPRP opposed Poland's war against Soviet Russia of 1919–21. During the fighting, the KPRP's legal status was legislatively taken away; the communist party would remain an underground organization in Poland until its demise. Due to the support for the government provided by pro independence socialists of the PPS, efforts by the KPRP to agitate for workers' solidarity with the Red Army were forestalled. However, at the height of the Red Army offensive the Provisional Polish Revolutionary Committee was formed on 2 August 1920. It consisted of Julian Marchlewski, Felix Dzerzhinsky, Feliks Kon, Józef Unszlicht, and Edward Próchniak. Its establishment brought no political gains for the party. The traditional Marxist position on the land question as understood by the Polish Marxists was abandoned, in favour of Vladimir Lenin's views.

The period 1921–1926 saw relative political freedom in Poland and the KPRP took advantage of the opportunities. Gains in membership were initially made from the ranks of the reformist workers' organisations and in the late 1920s from a left wing faction of the PPS, led by Stanislaw Lancucki and Jerzy Czeszejko Sochacki. They joined the KPRP, giving the party representation in the Sejm (Polish legislature). Gains were also made from the General Jewish Labour Bund in Poland when a faction led by Aleksander Minc joined and from two smaller Jewish socialist groups: Poale Zion and the United Jewish Socialist Workers Party (Fareynikte). In the eastern borderlands, the KPRP and then KPP operated as the autonomous Communist Party of Western Ukraine (KPZU) and Communist Party of Western Belorussia (KPZB); When railway workers went on strike, the PPS declared a general strike. "Even the tiny and illegal Polish Communist Party announced support for what they termed Piłsudski's 'revolutionary armies'." The railway workers were vital, because during the fighting they blocked troop trains trying to deliver reinforcements for the government. On 14 May, the government leaders decided to stop resisting the coup and resigned. During Piłsudski's May coup, the KPP engaged in street battles with troops loyal to the government of Wincenty Witos, which it called fascist. The KPP leaders directly aided the coup, for which they would pay a steep price. After the events Stalin sharply denounced the KPP leadership and they were eventually ousted for their "May error". The debate over the "May error" was getting increasingly venomous before and during the party's Fourth Congress in September 1927 in Moscow. In the aftermath, two representatives of the Comintern were placed on the Polish party's Central Committee: the Finn Otto Wille Kuusinen and the Ukrainian Dmitry Manuilsky; the KPP was no longer in a position to exercise any independence of thought and action. Despite the internal factional struggles, the party grew during this period, attracting support from the minorities and among the working class. It participated in the 1928 Polish legislative election. However, the removal of the Warski group from leadership resulted in the party plunged into isolation as it embarked on the "Third Period". Endorsed by the KPP's Fifth Congress in 1930, the Third Period saw the party routinely describing the PPS as fascist and revolution was claimed to be imminent. As the country was hit severely by the Great Depression, the KPP became embroiled in a new internal struggle.

The popular front strategy was pursued by the KPP in the mid 1930s. The KPP pressed both the PPS and Bund for unity, which both rebuffed. The communists tried to infiltrate organisations alien to the workers' movement, such as the Peasant Party and even Catholic groups. Unity of the Left remained an impossible goal, however. Many militants of the KPP joined the International Brigades to fight the Nationalists during the Spanish Civil War. The Dąbrowski Battalion, named for the hero of the Paris Commune, was led by the KPP but counted among its members many PPS workers and other non KPP volunteers.

In the mid and late 1930s the KPP became a victim of paranoia and suspicion that engulfed the Stalin led communist movement. It culminated in the Moscow Trials and purges. A number of KPP members were accused of being agents of institutions of Sanation Poland and liquidated. Next almost the entire leading cadre of the party became embroiled in the purges and murdered. Many were summoned to Moscow for "consultations". Among those killed were: Albert Bronkowski, Władysław Stein Krajewski, Józef Unszlicht, Adolf Warski, Maria Koszutska, Maksymilian Horwitz, Julian Leszczyński, Stanisław Bobiński, Jerzy Heryng, Józef Feliks Ciszewski, Tomasz Dąbal, Saul Amsterdam, Bruno Jasieński and Witold Wandurski. The leaderless party was then accused of Trotskyism among other "deviations" and 16.08.1938 dissolved by the Comintern. Most of the KPP activists perished in the Great Purge, but among those who survived were some of the future leaders of communist Poland.

The KPP was guided by Marxist ideology under a strictly orthodox interpretation. It opposed the establishment of a politically independent Poland. Its activists functioned as party members and government officials in Soviet Russia. The KPP was against land reform (distribution of property to landless peasants). It aimed to organize the working class and to unify the trade union movement. It adhered to policies established by the Comintern in Moscow. Its status was illegal, as it refused to register as a political party.

Arriving from the Soviet Union, a group of Polish communists was parachuted into occupied Poland in December 1941. With Joseph Stalin's permission, in January 1942 they established the Polish Workers' Party, a new communist party.