Memorialis is a series of books devoted to interesting historical events - the Crusades - wars for supremacy over the holy land, a region sacred to both Christians and adherents of the Muslim faith, which have been fought for two centuries. They involved such prominent personalities as Richard the Lionheart, Louis IX, Philippe-Augustus, Zangi, Beibars and many others. Considering the history of the bloody struggle from the point of view of both Christians and Muslims, the authors thereby avoid bias in the narrative. They pay great attention to the lessons of these campaigns, warning about the danger of historical parallelism.