To protect his own interests from the crusaders, the Grecian emperor made an alliance with Saladin. This made the former a greater object of hatred than ever before. In the first crusade, Alexius had been suspected and detested; Manuel had been openly blamed for the failure of the second crusade. Now in the third, no means are too odious to be attributed to the emperor of the East. In a years, the hatred accumulated for more than a century, will vent itself in the sack of Constantinople. See especially Riezler: Kreuzzug Kaiser Friedrichs I. in Forschungen zur Deutschen Geschichte, Vol.10.
Frederic, by the grace of God, emperor and always august, to his beloved kinsman Leopold, duke of Austria,--greeting and all good wishes.
We thought we ought to tell you, because of your love for us that our brother, the emperor of Constantinople, although he ought to have been bound by brotherly love, has from the very first violated all the oaths which are known to have been sworn by his chancellor at Nuremberg, in the presence of the princes of the empire, in regard to our security On the marsh, and markets and exchanges. Moreover, he has seized and ignominiously thrown into prison our ambassadors, the bishop of Munster, count Rupert and Markward, our chamberlain, together with all their attendants, whom we had sent to confirm the peace and to arrange for our peaceful march on this expedition of the quickening cross. At length, however, after long negotiations, grievously delaying our march until the dangerous winter season, he has sent back to our excellency the aforesaid embassadors on the feast of St. Simon and St. Jude, as if matters had been satisfactorily arranged, and he has again promised us good markets, the usual exchanges and an abundance of vessels.
Truly, because the burnt child dreads the fire, we can in the future
have no confidence in the words and oaths of the Greeks. In order to avoid the stormy winter season, we propose to stay until spring at Philippopolis and Adrianople and to cross over to Constantinople in the favorable season. Therefore, although we rejoice in a well-equipped army, yet we must seek divine succour in our prayers For these reasons we ask and desire of your love, that in your prayers and pious devotions you commend us and the whole army of the crusaders to God. In addition we ask of your prudence to see that the letters which we send to the pope reach him through your aid and exertions, because you can arrange this more succssfully than anyone else. (Adrianople, November 1189)
 Of Nassau.