Chronicles, letter and stories
The written historical sources concerning the invasion of 1361 consist of letters, contemporary chronicles and stories written down at a later date. A total of about 23 contemporary documents mention the invasion or related events. The sources date from 1361 to 1420.
The letters do not say much about the battles, but they give a general idea about the course of events. For example, they describe the Danish troop movements and those who were involved. Above all, they give an insight into the political situation. One chronicle from the Franciscan monks in Visby provides the dates of the battles and the numbers killed.
Regardless of whether the texts are contemporary or written much later, they must be read with a critical eye. They were often written with a political purpose that affects the description. There are a few chronicles from the 1450s and onwards that mention the invasion. The information in them is based on legends and older texts.