more useful to the german infantry were the two 280 mm railway guns. two 420 mm, two 355 mm howitzers were also available, along with four 305 mm mortars. both of the 420 mm guns were of first world war vintage, short in range and with limited ammunition. some nine 283 mm mortars were also available, but they were pre-1914 weapons and six had burst during firing. artillery acquired from czechoslovakia after the munich agreement, the skoda 305 mm model 1911 howitzer was also available. at the divisional level, 268 105 mm and 80 150 mm weapons were in service, including 126 nebelwerfer infantry barrage rocket launchers. overall, the german 11th army's artillery was a collection of modern, obsolete, and foreign-built weapons. for the offensive, 183,750 rounds of 105 mm and 47,300 rounds of 150 mm ammunition were stockpiled, enough for 12 days of firing.