 In the early 4th century, defence-in-depth seems to have become the strategy in the frontier area, with the Wall becoming less of a 'curtain' barrier and more reliance being placed on the forts as 'strongpoints'.The reforms of the emperors Diocletian and Constantine led to prosperity, in the south of the country at least, but this stability did not long outlast the death of Constantine in 337.The 330s and 340s saw a return to civil wars in the empire and, again, Britain was affected.