Final answer:
The linkage between heresy and treachery can be traced back to the 13th century in Europe, during a time of unrest and conflicts such as the Crusades.
Step-by-step explanation:
The linkage between heresy and treachery can be traced back to the 13th century in Europe. This was a time of unrest and conflicts, including the Crusades and the rise of mendicant orders of monks. The Fourth Crusade, for example, deviated from its intended goal of recapturing the Holy Land and instead sacked the Christian city of Constantinople. These historical events and developments contributed to the association of heresy and treachery.