In 1219, northern Estonia unwittingly became the site of an extraordinary social experiment. Thanks to a victorious battle fought on 15 June 1219 by Danish King Valdemar II during the Crusades near the future city of Reval against pagan inhabitants, an immediate Christianization campaign ensued, beginning with the recording of all existing settlements. Granting of the first vassal fiefs was initiated, which can be determined according to an annex to the so-called Liber Census Daniae from around 1241.