Pressure from the North (1430-1437)
The Kingdom of Denmark-Sweden was seen as a rival by the Holy Roman Empire and its emperor. This view was further solidified when Danish-Swedish influence began to increase in the northern Holy Roman states. Specifically the Duchy of Holstein was a primary target for the Scandinavians. The Danish-Swedish influence led to anger within the Holsteiner population, going as far as massive fights in the cities, to the point where the army actually had to step in in Lübeck. The situation got out of hand and the Holsteiner government contacted the emperor, informing him of the unrest in the duchy and the threat that Denmark-Sweden formed. The emperor gave his word that the entire empire would come to the aid of Holstein should Denmark-Sweden attack. The time to keep his word came in 1435, when Denmark-Sweden invaded the duchy after a group of Holsteiners slaughtered a Danish village.
more to come
Dutch Civil War (1438-1452)
Vinlandic War of Independence (1453-1456)
New England War (1493-1496)
Pressure Cooker in Louisiana (1498-1499)