He took part in the communist resistance against the occupation of the Netherlands during World War II by Nazi Germany, for which he was executed by the Germans in April 1942.

[2] He became a member of the Social Democratic Workers Party (SDAP) as well as the Dutch Association of Railway and Tramway Employees (NV) in 1902.

Back in the Netherlands, Sneevliet became active in the fledgling communist movement, becoming a salaried official of the party's National Labor Secretariat (NAS) and helping to organize a major transportation strike in 1920.

[2] The same year he was also present at the 2nd World Congress of the Communist International in Moscow as a representative of the Partai Komunis Indonesia (PKI), which was the successor to Sneevliet's ISDV.

[3] Sneevliet was an advocate of cooperation with the non-communist nationalist Kuomintang, headed by Sun Yat-sen, with whom he had personally established contact on behalf of the Comintern.

[2] He joined the executive committee of the Communist Party of Holland in 1925 but the two years were marked by worsening factional relations between Sneevliet and his co-thinkers and the bulk of the CPN leadership.

He remained interested in Indonesian affairs and in 1933 was sentenced to five months imprisonment for his solidarity actions for the Dutch and Indonesian sailors who took part in the mutiny on "De Zeven Provinciën", which was put down by an air bombardment in which twenty-three sailors were killed and which at the time aroused considerable passions in the Dutch public opinion.

[2] In August 1933, the RSP signed the "Declaration of the Four"[6] along with the International Communist League, led by Leon Trotsky, the OSP and the Socialist Workers' Party of Germany.

Sneevliet had informed Victor Serge that Reiss, a leading GPU official in the Netherlands was "heartbroken" by the Zinoviev Trial and had crossed over to the anti-Stalinist Opposition.

In his autobiography Serge described Sneevliet that day as thus: "his face wore a persistent frown amid its close lines, but he never lost heart.

[8] With James Maxton of the ILP, Sneevliet headed deputations to civil war Spain on behalf of the international campaign for socialists there persecuted after the May Days of Barcelona.

[7] The worsening political climate both abroad and nationally and the constant struggle against both the communist and social democratic parties, as well as government interference, took a heavy toll on Sneevliet and his small organization, however.

[9] This was largely engaged in producing propaganda for socialism and opposing the Nazi occupation of the Netherlands and as such was heavily involved with the February strike of 1941.