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PREFACE 
 The second volume of this work now lies before us at last. As the editors
of volume I promised and warned, the narrative continues the account there
set forth. It begins essentially with the critical events of 1189, and carries
on through the tumultuous decades of the thirteenth century to various suitable
stopping points a hundred years or so beyond the start. Only occasionally
- as in the first chapter, on the Normans, the fourth, on Byzantium, and
the eighteenth, on Armenia - will the reader find any considerable retrospect
into the earlier twelfth century, and this the authors always undertake with
an eye to the events of the late twelfth or thirteenth. In these cases we
try to pick up at their point of origin threads which, in the course of time,
wove themselves into the later fabric of events. 
 Once the operations of Richard the Lionhearted and Philip Augustus have
been completed, and those of Frederick Barbarossa and Henry VI brought to
their abortive ends, we focus our attention upon the Byzantine empire, against
which Henry, like so many of his Norman predecessors, had planned to sail.
With the tragic and controversial Fourth Crusade, the whole crusading enterprise
changes its complexion, as Christians overturn a Christian empire, and found
new states upon its dismembered territories - a development that not only
effectively destroys the hope of Christian unity against the Moslems and
sets Greek against Latin, but also divides the efforts of the western Europeans
themselves, who must now protect and support, defend and reinforce both their
establishments in the Levant and those in lands formerly Byzantine. This
dispersal of effort and frittering away of resources is further enhanced
as the popes of the thirteenth century begin to use the crusade first as
an instrument against the Albigensian heretics in their own western European
world, and then as a weapon in their private political quarrels. 
 Yet the efforts against the Moslems continue, of course, and once we have
chronicled these various thirteenth-century perversions of the crusading
undertaking, we move east once more for the operations of Pelagius and John
of Brienne in Egypt, for the spectacular diplomatic triumphs of Frederick
II (their lustre 
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