When the decennary societies ceased to exist, the connection between the peace officer and the particular group which he represented underwent a change, but the alteration was one of degree rather than one of kind. The fifteenth century constable was taught to look for the support of his fellow-citizens in case of need, though not to the same extent, perhaps, as the headborough was wont to rely on the members of his tything. The great principle of mutual responsibility remained, and was kept alive by insisting that all freemen should enter into a solemn obligation to keep the peace, a compact which, modified to suit more modern requirements, had its origin in the ancient oath of allegiance. The form of oath varied in different places; in London it was as follows--"You shall swear that you shall be good and true unto the King of England and to his heirs, Kings and the King's Peace you shall keep; and unto the Officers of the city you shall be obedient, and at all times that shall be needful, you shall be ready to aid the officers in arresting misdoers, and those disobedient to the King's Peace, as well denizens as strangers. And you shall be ready, at the warning of the Constables and Bedels, to make the watches and (to bear) the other charges for the safeguard of the peace, and all the points in this wardmote shown, according to your power you shall well and lawfully keep--and if you know any evil covin within the ward or the city, you shall withstand the same, or to your alderman make it known. So help you God and the Saints."[78] An examination of the oaths administered to constables and freemen respectively reveals to us in a concise form the motives which directed the mediæval machinery for maintaining the peace. We see how a compromise was arrived at between the ancient system of frankpledge and the more modern plan of employing a professional class of peace officers, and how, by means of the combined action of police and public, domestic tranquillity was assured. Had it been possible to have made this co-operation complete and thorough, the resulting security would have left little to be desired; but, as was only to be expected, discord not infrequently took the place of harmony, and freemen sometimes forgot what was due to the oath they had taken. Let the events of a certain night in Canterbury serve as an illustration. Some watchmen, it appears, challenged a man whom they found abroad "out of due time" and inquired his business, but (to continue the story verbatim) "the suspect person gave none answer, but ran from thence into St Austin's liberty, and before the door of one John Short they took him. And the same John Short came out of his house with other misknown persons and took from the said watchmen their weapons, and there menaced them for to beat, contrary to the oath of a true and faithful freeman."[79]