Under the rule of Hanu‘ Welfl of Varnsdorf, Sloup became part of restless Hussite Wars. The majority of the noble families of northern Bohemia, including Ronovec, Vartenberk, Birbštejn families and also nobility of rather local significance like for instance Hanu‘ Welfl, were against the Hussitism and remained faithful to the catholic side in this conflict.
In the first years of the Hussite Wars, northern Bohemia and the Ceská Lípa surroundings were saved from any acts of war. However, this area was threatened from time to time by smaller Hussite invasions, during which some towns were plundered. The first serious threat came in 1426 when the Hussites organized a military campaign into northern Bohemia which culminated into the battle at Ústí nad Labem. The Hussite army took some towns and the town of Mimon was burned down. The Ralsko castle withstood the siege. However, Lipá surrendered and after that became part of the Tábor town league called “sirotci” (Orphans, for opposing the majority of the towns).
As a result, Sloup was at once very close to the danger embodied by the Hussite garrison. However, the Hussite army never reached Sloup. Hanuš Welfl and other nobility of northern Bohemia were in connection with the neighbouring Lusatian towns, to which they constantly gave information about the moves of the Hussite army.