Karol Wacław Świerczewski (pronounced [ˈkarɔl ɕfjɛrˈt͡ʂɛfskʲi]; callsign Walter; 22 February 1897 – 28 March 1947) was a Polish and Soviet Red Army general and statesman. He was a Bolshevik Party member and served in the Soviet Red Army during the Russian Civil War and participated in the wars against the Polish and Ukrainian Republics. He also participated alongside the Republicans during the Spanish Civil War. At the start of World War II In 1939, he participated in the Soviet invasion of Poland. At the end of the war he was installed as one of leaders of the Soviet-sponsored Polish Provisional Government of National Unity. Soon later, Świerczewski died in a country-road ambush shot by the militants from OUN-UPA. He was an icon of communist propaganda for the following several decades.

Born in Warsaw in Congress Poland, Karol Świerczewski grew up in a poor working-class family and began working at age 12 in a local Warsaw factory. During the First World War, at the age of 18 he was evacuated in 1915 to Moscow by the Russian Imperial Army. According to his official biography in the Polish People's Republic he was a member of the Social Democracy of the Kingdom of Poland and Lithuania.

In 1918 he joined the Bolshevik Party, and fought in the Russian Civil War as a soldier of the Red Army. In 1919 during the Polish-Soviet War he fought on the Soviet side against the Polish Second Republic and was wounded. He remained in Russia and in 1928 on the occasion of the 10th anniversary of establishment of the Red Army he was awarded the Order of the Red Banner (no. 146), his first military award. From 1921, Świerczewski taught in the Soviet School for the Red Commissars. In 1927 he graduated from Frunze Military Academy in Moscow and worked in the Red Army General Staff.^{[citation needed]}

In 1931-1933 and maybe later Świerczewski was heavily involved in armed insurrection trainings, delivered by Comintern to Spanish communists in Moscow. His direct role is inclear, though he later produced highly detailed reports on the classes given; he suggested a number of measures to improve their quality. Already at the time he used the nick-name Walter. In late 1935, when officer ranks were introduced in the Soviet Army, Świerczewski was classified as colonel.

In 1936, under the name General Walter, he was sent to Spain during the Spanish Civil War, where he initially led the XIV International Brigade in the Battle of Lopera, and later the 35th International Division in the Segovia offensive, and the battles of Brunete, Belchite, Teruel, and the Aragon Offensive. By April 1938 Spanish communist leaders wanted the replacement of many International Brigade commanders due to poor performance, and although André Marty disagreed, he had to compromise and General Walter and Vladimir Ćopić were replaced.

In June 1940 Świerczewski was promoted from colonel to the lowest general rank, general major. Following the outbreak of the Second World War and the Soviet invasion of Poland, Świerczewski served as general in the Soviet Army. On June 27, 1941 he was given command of the 248th Rifle Division as it began forming at Vyazma. He led the division until it was largely encircled and destroyed during Operation Typhoon in the first weeks of October, although he remained in nominal command until late December. His Russian commanders, seeing Świerczewski's apparent incompetence and worsening alcoholism, moved him to a reserve command away from the front lines—the decision was made by General Georgi Zhukov himself. The fact that Świerczewski gave most of his orders under influence of alcohol had tragic consequences for his soldiers, described in General Zygmunt Berling's book Wspomnienia (Memories).

In 1943 he became one of the generals charged with the creation of the Soviet-controlled Polish Armed Forces in the East, the 1st Polish Army. His alcoholism and disregard for the life and health of his soldiers stirred conflict with Zygmunt Berling, and led to his removal from command on several occasions. Świerczewski's alcoholism-related orders gained criticism from other Polish generals as well, including General Aleksander Waszkiewicz.

In 1944 he became one of the leaders of the Polish Workers' Party and the government of People's Republic of Poland. In the winter of 1944 and the spring of 1945 he led the Polish Second Army during the fighting for western Poland and the Battle of Berlin. His leadership in the Battle of Bautzen (Budziszyn) has been severely criticized by modern historians, and he is held responsible for the Second Army's very heavy casualties in that engagement. While commanding, he might have been drunk, and was temporarily relieved of his command. However, due to important backing in the Soviet political apparatus (Main Intelligence Directorate or NKVD), not only did he retain his command, but his mistakes were hushed up, and after the war he was glorified as a hero.