Theoderic participated in the Siege of Damascus, led by his wife's half-brother Baldwin III of Jerusalem, and with the support of Baldwin, Louis VII of France, and Conrad III of Germany, he lay claim to Damascus. However, the native crusader barons preferred one of their own nobles, Guy I Brisebarre, lord of Beirut. According to William of Tyre, the resulting dispute contributed to the final failure of the siege: 'for the local barons preferred that the Damascenes should keep their city rather than to see it given to the count', and so did all they could to ensure the siege collapsed. Therefore, William continues, many contemporaries blamed Theoderic for the ultimate failure of the Second Crusade (though it is notable that William himself declines to say whether he believed Theoderic responsible).