How did the Crusades give birth to Renaissance in Italy?

Let me say something about this question. It seems to me that Crusades had very weak linkage to Renaissance. However, I have read some information that the fall of Crusades and their related powers in Middle East had a great impact to the authority of papacy. So countries in Europe started to have more freedom to develop themselves. And the countries in Italy were very rich at that time, the thirty-years war also made the middle and western Europe a ruin, so the Italian countries attracted many brilliant scientists, artists, writers and so on to these countries, then Renaissance began.

The Crusades were a series of religion driven military campaigns waged by much of Christian Europe against external and internal opponents. Crusades were fought mainly against Muslims, though campaigns were also directed against pagan Slavs, Jews, Russian and Greek Orthodox Christians, Mongols, Cathars, Hussites, Waldensians, Old Prussians and political enemies of the popes. Crusaders took vows and were granted an indulgence for past sins.

The Crusades originally had the goal of recapturing Jerusalem and the Holy Land from Muslim rule and were launched in response to a call from the Eastern Orthodox Byzantine Empire for help against the expansion of the Muslim Seljuk Turks into Anatolia. The term is also used to describe contemporaneous and subsequent campaigns conducted through to the 16th century in territories outside the Levant usually against pagans, heretics, and peoples under the ban of excommunication for a mixture of religious, economic, and political reasons. Rivalries among both Christian and Muslim powers led also to alliances between religious factions against their opponents, such as the Christian alliance with the Sultanate of Rum during the Fifth Crusade.

The Crusades had far-reaching political, economic, and social impacts, some of which have lasted into contemporary times. Because of internal conflicts among Christian kingdoms and political powers, some of the crusade expeditions were diverted from their original aim, such as the Fourth Crusade, which resulted in the sack of Christian Constantinople and the partition of the Byzantine Empire between Venice and the Crusaders. The Sixth Crusade was the first crusade to set sail without the official blessing of the Pope. The Seventh, Eighth and Ninth Crusades resulted in Mamluk and Hafsid victories, as the Ninth Crusade marked the end of the Crusades in the Middle East.