A feud letter (German: Fehdebrief or Absagebrief) was a document in which a feud was announced, usually with few words, in medieval Europe. The letter had to be issued three days in advance to be legally valid.
To prevent the feud from becoming a case of murder and thus become punishable by law, those involved had to abide by the following rules:
Around 1444, the town of Soest declared war on the Archbishop of Cologne at the start of the Soest Feud with the following famous, brief feud letter:
"Wettet, biscop Dierich van Moeres, dat wy den vesten Junker Johan van Cleve lever hebbet alls Juwe, unde wert Juwe hiermit affgesaget"
("Know this, Bishop Dietrich of Moers, that we prefer the steadfast Junker, John of Cleves, to you, and hereby give you notice thereof.")