This system, around which the economic life of Virginia centered for a full century, proved satisfactory to all concerned. The credit advanced to the immigrant made it possible for him to earn his ocean fare, not in England where labor was cheap, but in America where it was dear. In other words, he was enabled without delay to enjoy the full benefits of selling his services in the best market. The necessity for placing him under a stringent contract or indenture is evident. Had this not been done the immigrant, upon finding himself in Virginia, might have refused to carry out his part of the bargain. But the indenture was in no sense a mark of servitude or slavery. It simply made it obligatory for the newcomer, under pain of severe penalties, to work out his passage money, and until that was accomplished to surrender a part of the personal liberty so dear to every Englishman. It is erroneous to suppose that most of the servants were degenerates or criminals. It is true that the English Government from time to time sought to lessen the expense of providing for convicted felons by sending some of them to the colonies, among them on rare occasions a few decidedly objectionable characters. More than once the Virginians protested vigorously against this policy as dangerous to the peace and prosperity of the colony.[2-23] By far the larger part of these penal immigrants, however, were but harmless paupers, driven perhaps to theft or some other petty offense by cold and hunger. Often they were sentenced to deportation by merciful judges in order that they might not feel the full weight of the harsh laws of that day.[2-24] And of the small number of real criminals who came in, few indeed made any lasting imprint upon the social fabric of the colony. Many served for life and so had no opportunity of marrying and rearing families to perpetuate their degenerate traits. Those who escaped fled from the confines of settled Virginia to the mountains or to the backwoods of North Carolina. Many others succumbed to the epidemics which proved so deadly to the newcomers from England. In fact the criminal servant was but a passing incident in the life and development of England's greatest and most promising colony.[2-25] An appreciable proportion of the so-called criminal laborers were no more than political prisoners taken in the rebellions of the Seventeenth century. These men frequently represented the sturdiest and most patriotic elements in the kingdom and were a source of strength rather than of weakness to the colony. When Drogheda was captured by Cromwell's stern Puritan troops in 1649, some of the unfortunate rebels escaped the firing squad only to be sent to America to serve in the sugar or tobacco fields. Just how many of these Irishmen fell to the share of Virginia it is impossible to say, but the number rises well into the hundreds, and the patent books of the period are full of headrights of undoubted Irish origin.[2-26]