sentences:  Gunpowder weapons had begun to be introduced into England in the early 14th century, initially being used as offensive siege weapons but rapidly being adapted for defensive purposes during the 1360s.Although they were expensive, by the 1380s their potential value in defending castles and city walls was well understood and specialised facilities had begun to be built.Norwich had acquired gunpowder weapons and a team of gunners by 1355, and by 1385 had fifty gunpowder pieces for use along its city walls.