[1] Henrik Horn was born at Stade in the Prince-Archbishopric of Bremen, today in Lower Saxony, Germany, into a Swedish noble family of medieval origin.
He distinguished himself in the Polish campaign and in 1666 was appointed Governor-General of Bremen-Verden which was under a Personal union with Sweden from –1712.
[citation needed] As Governor-General he commanded Swedish forces in 1675/76 against the allied German armies during the Bremen-Verden Campaign, but eventually had to surrender.
He was given the command of the Royal Swedish Navy in 1677 and was made a member of the Privy Council of Sweden (riksråd).
In 1680, Horn left Livonia and returned to help rebuild Stade which had been besieged in 1676 during the Swedish-Brandenburg War.