A Feather in One'S Cap

In the Lansdowne manuscript in the British Museum is a description of Hungary in 1599, in which the writer says of the inhabitants, "It hath been an antient custom among them that none should wear a fether but he who had killed a Turk, to whom onlie yt was lawful to shew the number of his slaine enemys by the number of fethers in his cappe."