Janusz Radziwiłł trust in the Poles was damaged during the Battle of Vilnius in 1655 when he, being the Great Hetman of the Grand Duchy of Lithuania, had to defend the Grand Duchy's capital Vilnius from the approaching Tsardom of Russia forces. When a large Russian army approached Vilnius (at least 41,000 men), Janusz Radziwiłł could muster just 5,000 to 7,000 men. The morale was further damaged by the order of king John II Casimir Vasa to royal troops (about 5,000 men) to retreat to Marienburg. City residents began hasty evacuations. Most valued treasures, including the coffin of Saint Casimir, main books of Lithuanian Metrica, and valuables from Vilnius Cathedral, were transported outside the city.