Henrik Ruse, Baron of Rysensteen (Henrick, Hendrick, Hendrik, Henri, Henry; Rusensteen, Russenstein, Rusenstein), né Henrik Ruse (Rüse, Rusius, Ryse), (9 April 1624 - 22 February 1679) was a Dutch officer and fortification engineer. Following a period when he served in various armies in Germany and Italy, he wrote a well-researched book documenting the latest trends in fortification systems across Europe. As a result, he was entrusted with commissions for improving defences in his native Amsterdam, in Germany, and finally in Denmark and Norway where, benefitting from the support of the monarchy, he first became a general and later a baron. Ruse died in Sauwerd near Groningen in the Netherlands.
Ruse was born in the village of Ruinen in the Dutch province of Drenthe. His father, Johan Ruse, who was the parish priest in Ruinen, belonged to a Hugenot family from eastern France, sympathising with the Protestant theologian Jacobus Arminius. Unlike his brothers who studied in Franeker, at the age of 15 Ruse began a military career where he saw action under the flags of France, Weimar and Venice.
He took part in the Battle of Freiburg (1644), the Battle of Alerheim (1645) and was active at Philippsburg, serving the Prince de Condé, the Vicomte de Turenne and the Duke of Saxe-Weimar. In 1646, he went to Bergamo and Venice and served under General Leonardo Foscolo in Dalmatia. In 1648, the Venetian army occupied Dugopolje and moved up to the Ragusa. As the Turks had occupied the island Crete the Venetian army went as far as Risan, Bar and Budva in order to occupy Albania. When Foscolo was appointed in Candia in 1651, Ruse decided to leave the army because of problems with his legs, and on his way back, he paid great attention to defence systems and facilities.