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Ch. X POLITICAL CRUSADES OF THIRTEENTH CENTURY 369 
would be fatal to his hopes of restoring the Christian position in Palestine.
He devoted his whole pontificate to an attempt to promote a new crusade;
he used Charles's ambitions only as a means of furthering his main objective.
If the threat of an Angevin invasion could frighten Michael Palaeologus into
cooperating with the Roman church so much the better, but Gregory was not
going to allow any large expedition to waste western resources in an attack
on the Greeks. 
 Michael made almost the same estimate of the situation as the pope, which
made it easy for Gregory to carry out his policy. Faced with the Angevin
threat, the emperor agreed to the union of the churches in 1274 and suggested
that he might aid the new crusade. The union was bitterly opposed by the
Greeks, but Michael was harsh enough with the dissenters to convince the
pope of his good faith. Gregory could not prevent minor skirmishes in Greece
and the Balkans, but he did restrain Charles from launching a major expedition.
Nicholas III followed the same policy, even though by his time it was apparent
that the union would be a failure. 
 Charles must have suffered during these years of frustration, but he never
made the mistake of directly and openly opposing the pope. He waited patiently,
gained all the support he could in the college of cardinals, and finally
reaped his reward. In 128 1 the Frenchman Simon of Brie, an old friend of
the Capetian family, became pope under the name Martin IV. At last all the
pieces of the long-planned combination against the Byzantine empire were
going to fit into place. 
 At first all went well. The Greek emperor was excommunicated for his failure
to make the union effective. Venice joined the alliance against the Byzantines
and promised important naval sup port. Charles began to raise money and troops.
The pope granted him the crusade tenth in Hungary and Sardinia, and crusade
legacies and redemption of vows in Sicily and Provence. There was a certain
ambiguity in these grants; Martin IV declared that they were to be used against
the "infidel", and thus did not directly sanction a crusade against the schismatic
Greeks.14 The official French historian, William of Nangis, took the same
view; he ignored Charles's obvious plans to attack the Byzantine empire and
declared that he was going to fight the Saracens and reconquer the kingdom
of Jerusalem.15 But Bartholomew of Neocastro, 
14 Les Registres de Martin IV, Bibliothêque des Ecoles francaises d'Athènes
et de Rome, ser. 
2, vol. XVI, part I (Paris, 1901), nos. 116, 117. 
15 RHGF, XX, 516. For Charles's claim to the kingdom of Jerusalem, see below,
chapter 
XVI, pp. 583—591.