Answer by taking a quote from the following article:

De Ruyter was born on 24 March 1607 in Vlissingen, Netherlands, as the son of beer porter Adriaen Michielszoon and Aagje Jansdochter. Little is known about De Ruyter's early life, but he probably became a sailor at the age of 11. It is said that once, when he was a child, he climbed up ladders to get to the roof of his home town's church. Not knowing that De Ruyter was there, some workers then removed the ladders.

In July 1655, De Ruyter took command of a squadron of eight (of which the Tijdverdrijf [Pastime] was his flagship) and set out for the Mediterranean with 55 merchantmen in convoy. His orders were to protect Dutch trade. Meeting an English fleet under Robert Blake along the way, he managed to avoid an incident. Operating off the Barbary Coast, he captured several infamous corsairs. After negotiating a peace agreement with Sale, De Ruyter returned home May 1656.  The same month, the States General, becoming ever more wary of Swedish King Charles X and his expansion plans, decided to intervene in the Northern Wars by sending a fleet to the Baltic Sea. The Swedes controlled this area after Charles had invaded Poland and made himself king there. De Ruyter once again embarked aboard the Tijdverdrijf, arriving at the Oresund 8 June; there he waited for Lieutenant-Admiral Jacob van Wassenaer Obdam to arrive. After Obdam had assumed command, De Ruyter and the Dutch fleet sailed to relieve the besieged city of Danzig/Gdansk on 27 July, without any bloodshed. Peace was signed a month later. Before leaving the Baltic, De Ruyter and other flag officers were granted an audience by Frederick III of Denmark. De Ruyter took a liking to the Danish king, who later became a friend.  In 1658, the States General, on the advice of a leading member (Cornelis de Graeff, one of the mayors of Amsterdam), decided to once again send a fleet to the Baltic Sea to protect the important Baltic trade and to aid the Danes against Swedish aggression, which continued despite a peace settlement. In accordance with the States' balance-of-power political approach, a fleet under Lieutenant-Admiral Jacob van Wassenaer Obdam was sent, without De Ruyter, who at the time was blockading Lisbon. On 8 November, a bloody melee took place, the Battle of the Sound, which resulted in a Dutch victory, relieving Copenhagen. Still the Swedes were far from defeated and the States decided to continue their support. De Ruyter took command of a new expeditionary fleet and managed to liberate Nyborg in 1659. For this, he was knighted by King Frederick III of Denmark From 1661 until 1663, de Ruyter did convoy duty in the Mediterranean.

What happened to his forces
In 1658, the States General, on the advice of a leading member (Cornelis de Graeff, one of the mayors of Amsterdam