On September 8 General Heinz Guderian, commander of the XIX Panzer Corps, was ordered to advance through Wizna towards Brześć. By early morning of September 9 his units reached the Wizna area and were joined with 10th Panzer Division and "Lötzen" Infantry Brigade already present in the area. His forces numbered some 1,200 officers and 41,000 soldiers and NCOs, equipped with over 350 tanks, 108 howitzers, 58 pieces of artillery, 195 anti-tank guns, 108 mortars, 188 grenade launchers, 288 heavy machine guns, and 689 machine guns. Altogether, his forces were some 60 times stronger than the Polish defenders.