on 24 may, the 1st panzer division reached the aa river and established bridgeheads on its north bank at holque, st pierre-brouck, st nicolas and bourbourgville. 2nd panzer division was still busy finishing up the conquest of boulogne, but the allied resistance had been decisively weakened, meaning that some of its forces could be pulled out to aid combat elsewhere. the main force of 10th panzer division advanced to the line desvres-samer. guderian's force was strengthened on may 24, when 1st ss panzer division "leibstandarte adolf hitler" was joined into xix army corps. 1st ss panzer was tasked with supporting 1st panzer with an attack on watten, in which it was to be reinforced by 2nd panzer after its victory at boulogne. in the meantime, 10th panzer division had encircled calais and began the siege of calais. guderian tasked 10th panzer's commander ferdinand schaal with a delayed approach, as 10th panzer was to be reinforced by heavy artillery from boulogne. parallel to xix army corps' advance, reinhardt's xli corps had taken saint omer. the operation was cut down decisively around noon, upon the personal intervention of adolf hitler.