Forerunners of the Reformation-Haley's Bible Handbook
"Albigenses or Carthari in southern France, Northern Spain and Northern Italy, preached against the immoralities of the priesthood, pilgrimages, worship of the saints and images, completely rejected the clergy and its claims of the Church of Rome, made great use of the scriptures; lived self- denying lives and had great zeal for moral purity. By 1167 they embraced possibly a majority of the population of South France; by 1200 very numerous in Northern Italy. In 1208 a crusade was ordered by Pope Innocent 3; a bloody war of extermination followed, scarely paralled in history; town after town was put to the sword, and the inhabitants murdered without distinction of age or sex; in 1229 the Inquisition was established and within a hundred years the Albigenses were utterly rooted out. The histories show that the 'Carthari' (meaning Puritans or 'pure ones') were also influenced by the Bogomils in Bulgaria.
History shows that many thousands of believing Christians throughout Europe and the British Isles clung to the 14th of Nisan as the true date for the observance of the Lord's Supper; that it required many hundreds of years for this practice to be stamped out. Even today, remants of the 'Waldenses' exist in Italy and are the largest Protestant group in that country. Their name is variously determined as coming from Peter Waldo, or their habit of dwelling in the valleys of remote alpine regions in Northern Italy, Switzerland, and France.
Waldo, a rich merchant of Lyons, South France (1176), gave his property to the poor and went about preaching, opposed clerical usurpatiion and profligacy; denied the exclusive right of the clergy to teach the Gospel, rejected masses, prayers for the dead and purgatory; taught the Bible as the sole rule of belief and life; their preaching kindled a great desire among the people to read the Bible. They were gradually repressed by the Inquisition except in the Alpine Valleys southeast of Turin, where they still are found, the only medieval sect surviving, a story of heroic endurance of persecutions. Now the leading Protestant body in Italy. P.785."

(The Bogomils, Albigensians, Petrobrusians, Arnoldists, Vaudois, and other sects, who were mostly termed 'heretics', included many who were 'Sabbatarians' and those who kept the annual Sabbaths as well.
This is why the Quartadeciman controversy raged for so long. Many of them observed the 14th of Nisan as Christ had commanded.
The apostles never celebrated Easter or ever taught any one else to do so.)