Manuel António Carlos was a crew member on the Greek ship Antonis when it was boarded by the German auxiliary cruiser Kormoran on January 6, 1941. Although Greece had not yet entered the war, the vessel was carrying three English machine guns and almost five tons of Welsh coal, reasons enough for the Germans to seize it.

The ship was sunk and the crew imprisoned.

In addition to Manuel António Carlos, the Portuguese Venâncio Almeida was also on board. On February 7, off Cape Verde, the Kormoran met with the Nordmark, a supply vessel to which about 170 seafarers imprisoned on several Allied ships were transferred.

Nordmark returned to France, possibly in May, with around 800 Allied prisoners on board. The seafarers were transferred to the Marlag and Milag Nord prison camp, north of Bremen, a camp designed to house the crew of merchant ships.

Manuel Carlos was assigned the prisoner number 88967, while Venâncio de Almeida was assigned the number 88966. In August 1943 the Ministry of Foreign Affairs received from the British authorities a list of several names of Portuguese seafarers in detention, in which both men are mentioned as being prisoners in Marlag and Milag Nord without receiving any financial support.

Five of these mentioned Portuguese were held until February 1944, when, through the intervention of the Portuguese government, they were released and sent by train to Lisbon. Manuel Carlos lost his teammates during the trip and reached the city on the 19. The next day it was the turn of Venâncio de Almeida, Florêncio da Silva, João da Cruz and Manuel Lopes Brioso to arrive.