I can’t see any modern pope going out of his way to defend the Crucades, knowing what we do about what actually happened.
It was an unmittigated murderous plunder and land grab despite the ostensible intention to free the Holy Land from the Muslims who had invaded it. Nothing that happened during the Crucades are any credit to Christians and the message of the Gospels.
There is a lot of information out on the Crucades and I’m afraid to say that the Muslims come out with a better reputation than the Christians that fought in the Holy Land in terms of mercy and tolerance.
I am not persuaded of this, and I am certainly not persuaded that “the Muslims” were a unitary force. They most certainly were not.
Initially, the Crusades resulted in the Byzantines regaining much of the land they had lost to the Turks. The Crusaders didn’t have to hand that territory to the Byzantines, but they did. At various times, Muslim Arab leaders joined with the Crusaders in fighting the Seljuk and Khwarasmian Turks, who were oppressing the Arabs. Right at the end, the Crusader states offered to join with the Mamluk Turks in Egypt in resisting the Mongol invasion that had pretty much destroyed Iraq. But the Mamluks refused. Finding themselves opposed by both, the Crusaders withdrew. The Mamluks then beat back the Mongols and took over most of the Middle East. But only for a time.
The oppression of the Arab Muslims by Central Asians didn’t end there. After being ruled (unwillingly) by the Mamluks, they were overwhelmed by Timur, another Turkic fellow from Central Asia, who essentially destroyed the Middle East; a destruction from which it really never recovered. In the meantime, the Ottoman Turks took over Asia Minor and fought Timur’s minions to a mutually destructive standstill, with the Arab lands as the unwilling battlefield. That gave Byzantium a breather, but only for a short while. Ultimately, the Ottomans took over the entire Middle East except for Persia, and misruled it for centuries.
Arabs are totally wrong in blaming the Crusaders for destroying their world. They were already ruled by Turks when the Crusaders came, and were ruled by other Turks when the Crusaders left, all the way down to the 20th Century.
When it comes to the Fourth Crusade, there was plenty of blame to go around, but the Pope did not bear any of it. It has to be remembered that the Frankish knights numbered perhaps as many as 8,000 men. The Byzantines promised (among other things) 10,000 Byzantine troops to aid in retaking the Holy Land. But the two warred on each other, and it came to nothing.
8,000 Franks conquered Byzantium in the Fourth Crusade. It was a bad thing, and the Pope excommunicated them all for it, but again, both sides were blameworthy. The Byzantines did recover from it, though it may be argued that they would have been stronger but for the Fourth Crusade.
Regardless, Constantinople, which had been taken by 8,000 Franks without artillery was later overwhelmed by 200,000 Ottoman Turks with the very latest artillery. It had absolutely no chance against a force like that, Fourth Crusade or no Fourth Crusade. It is unlikely that the western Christian countries could have come to the Byzantines’ aid in sufficient force to have saved them from that onslaught. Indeed, the later attempted Ottoman conquest of western Europe was a close thing, even though the westerners had shorter communication and supply lines.
The “western end” of the Crusades was more successful; that is, the eviction of Muslims from France and the Christian reconquest of Spain. Ultimately, the Austrians, Germans and Poles prevented the Ottomans from overwhelming western Europe. But again, it was a close thing. The Ottomans got all the way to the gates of Vienna, and had Vienna fallen, northwestern Europe would have been open to them. The Ottomans took the whole of the Balkans to the Adriatic, even so.