Louis Paulsen (15 January 1833 in Gut Nassengrund near Blomberg, Principality of Lippe – 18 August 1891) was a German chess player.
He put forward the idea that any brilliant attack would have failed against correct defence.
His ideas were grasped by Wilhelm Steinitz, who declared that attack and defence have equal status, and particularly by Aron Nimzowitsch, who listed Paulsen among his six greatest "purely defensive players".
Paulsen played in the final match of the 1857 First American Chess Congress, losing to Paul Morphy five games to one with two draws.
[5] It was played frequently by Henry Bird that decade, then received general acceptance around 1900.