Before the treaties of February, 1778, between the United States and France, the disposing of prizes captured by American vessels in French ports was exceedingly informal. Since France was obliged to at least make a pretence of observing her treaties with England and the laws of neutrality, she could not permit a trial of American prize cases in her admiralty courts. Consequently, prizes captured by American vessels were disposed of without trial and legal condemnation; they were taken into the offing of French ports and secretly sold to French merchants at a great sacrifice to the captors. After February, 1778, the prizes were legally tried, but not according to a uniform practice. Some cases were tried by the French admiralty courts; but in other cases the French courts prepared the _proces verbaux_, which they sent to Franklin; he then condemned the prizes and ordered the court to sell them. After July, 1780, Franklin ceased to exercise such judicial functions.[330] One of the objects of the cruises of Continental vessels in European waters was to capture Englishmen and exchange them for American naval prisoners languishing in prisons in England. These imprisoned Americans were confined chiefly at Forton prison at Portsmouth, and Mill prison at Plymouth. A list of prisoners confined at Mill prison during the Revolution, which contains 947 names, has been made out.[331] In April, 1782, there were eleven hundred Americans in the jails of England and Ireland, all committed to prison as charged with high treason.[332] A few Americans were confined at Gibraltar. These prisoners often suffered greatly from a lack of sufficient food, clothing, bedding, and fuel. This was in part caused by the cruelty and fraud of those whom the British government entrusted with the supply and control of its prisons. The rigors of their captivity were softened, and their deprivations in a measure relieved by money which Franklin sent from Paris, and by private subscriptions in their behalf made by generous Englishmen. To escape their penury and distress some prisoners enlisted in the enemy’s navy, or joined the British whaling fleets. Others escaped from prison; some of these burrowed their way out, committing treason through His Majesty’s earth, to use a phrase of Captain Conyngham, who, with sixty companions, in this way escaped from Mill prison in November, 1779. These escaped prisoners gradually found their way into Holland, the seaports of France, or even Paris; and they often became a tax upon Franklin’s pity, and the Continental treasury in his keeping. Franklin was deeply moved by the sufferings of these men, whether confined in England or at liberty in France. His efforts in their behalf are an important part of his work and achievements in France.