The attempted conversion of the Irish to Protestantism was generally a failure. One problem was language difference. The Protestant clerics imported were usually all monoglot English speakers, whereas the native population were usually monoglot Irish speakers. However, ministers chosen to serve in the plantation were required to take a course in the Irish language before ordination, and nearly 10% of those who took up their preferments spoke it fluently. Nevertheless, conversion was rare, despite the fact that, after 1621, Gaelic Irish natives could be officially classed as British if they converted to Protestantism. Of those Catholics who did convert to Protestantism, many made their choice for social and political reasons.