[1] After the outbreak of the war between Sweden and Denmark-Norway, the Dutch-Swedish industrialist Louis De Geer in 1644 equipped at his own expense, a Dutch squadron under Thijssen, in order to strengthen the Swedish navy.

When he learned of the new threat, Christian IV of Denmark broke the siege of Gothenburg, and sailed to meet the Dutch.

Soon enough it returned to Scandinavian waters, chasing away the Danish ships blockading Gothenburg, then sailing through the Sound to Kalmar.

When the peace with Denmark was concluded, he commanded the naval force that escorted a Swedish trading expedition to Portugal.

On the return voyage, Anckarhielm engaged a six-hour skirmish with two English warships which demanded he strike his colours off the Isle of Wight.