He returned to Africa in the 1950s and was involved in promoting the causes of independence of the then Portuguese colonies. In 1956, he founded the PAIGC (African Party for the Independence of Guinea and Cape Verde).
Cabral led the guerrilla movement of PAIGC against the Portuguese government in Guinea Bissau, which developed into one of the most successful wars of independence in African history. The ambition was to achieve independence for both Guinea Bissau and Cape Verde.
Cabral trained the villagers from Guinea through various techniques, including mock conversations to provide them with effective communication skills, which would help their efforts to mobilize Guinean tribal chiefs to support the PAIGC.
As an agronomist, he taught his troops to teach local crop farmers better cultivation techniques. This way, they could increase productivity and were able to feed their own family and tribe, in the same way that soldiers enlisted in the PAIGC.
Cabral led a huge International Diplomatic activity obtaining the support from a wide number of countries. In 1972, Cabral began to form a People’s Assembly in the preparation for the independence of Guinea-Bissau. However, disgruntled former PAIGC rival Inocêncio Kani, with the help of Portuguese agents operating within the PAIGC, shot him and killed him. The assassination took place on 20th January 1973 in Conakry, Guinea. His half-brother, Luís Cabral, became the leader of the Guinea-Bissau branch of the party and would eventually become President of Guinea-Bissau.
Other than being a guerrilla leader, Cabral was highly internationally regarded as one of the most prominent African thinkers of the 20th century. His intellectual contributions aimed at formulating a coherent cultural, philosophical and historical theoretical framework to justify and explain independence movements were also well known. This is reflected on his various writings and public interventions.