Although the Revenue cruisers were employed primarily and ordinarily for the purpose of protecting the revenue, yet from time to time they were mobilised for coast defence.  On different occasions during the eighteenth century they were lent to the Admiralty, and well supplied with men and arms in readiness for actual warfare.  After the third quarter of the eighteenth century these Revenue cruisers seem to have been built in greater numbers and with some improvement as to design, which, seeing that they had so frequently been left well astern by the smuggling cutters, was more than necessary.  There was issued in November of 1780, by the Board of Customs, an interesting letter that shows how closely these cruisers approximated to vessels of war, even when they were not under the jurisdiction of the Admiralty.  This letter was sent to the Collector and Controller at the different English Customs ports, and began by referring to the fact that many applications had been made to the Board asking permission to take out Letters of Marque.  It will be remembered that this was a time when wars seemed to go on interminably, and there had been only a few brief intervals of peace ever since the Anglo-Dutch wars began.  The Commissioners replied that they had no objection to the commanders of the cruisers providing themselves with Letters of Marque, if done at the latter’s own expense “during present hostilities”:  but the Board declined to bear any part of the expense for any damages that might be sustained in an engagement where no seizure had been made and brought into port for a breach of the Revenue laws, so long as a commander should continue to hold these Letters of Marque.  It was, in fact, a basis of no cure no pay.  Each commander was, further, strictly enjoined not to quit his station and duty as a Revenue officer “under pretence of looking for captures, it being our resolution to recall the permission hereby granted, as soon as it shall be discovered in any instance to be prejudicial to our service.”

But this war-like and semi-war-like service was entirely subservient to their ordinary work.  It is evident from the correspondence of the Customs Board of this same year, 1780, that their minds were very uneasy.  The smugglers, far from showing any slackening, had become more active than ever.  These men had, to quote the words of the Commissioners, considerably increased the size and force of their vessels; they had also added to their number of both men and guns.  They had become so violent and outrageous, they had acquired so much audacity as to “carry on their illicit designs in sight of the Revenue cruisers,” and “whenever they have appeared within a certain distance have actually fired into and threatened to sink them.”  In such cases as these, it was reported to the Board, the mariners on board these cruisers have frequently refused to bear down and repel their attacks, explaining their conduct by saying that no provision was made for their support in case