Passage: The strategic and economic importance of the city made Stockholm an important factor in relations between the Danish Kings of the Kalmar Union and the national independence movement in the 15th century. The Danish King Christian II was able to enter the city in 1520. On 8 November 1520 a massacre of opposition figures called the Stockholm Bloodbath took place and set off further uprisings that eventually led to the breakup of the Kalmar Union. With the accession of Gustav Vasa in 1523 and the establishment of a royal power, the population of Stockholm began to grow, reaching 10,000 by 1600.

Question: In what year did Christian II enter Stockholm?
1520