Regardless, the Castilian ships continued to attack the English, now as outright pirates. They had converted their vessels into warships by the addition of wooden castlesraised fighting platformsat the bow and stern and the erection of crow's nest fighting platforms at the masthead. They were based out of Sluys, and several hundred Flemish adventurers joined their ranks, mostly equipped as crossbowmen, in the expectation of plunder. Their assault on English shipping has been described as "ferocious", and as bringing "panic" to English ports. The English arrayed the coastguard for the first time since the Normandy campaign.