A lecture was given recently by former History professor Alfred Andrea, of the University of Vermont at the Waterman Lounge. The presentation was well-sourced, and he has certainly kept a speaking capability which has not suffered after 15 years in retirement. One thesis was included, that the conquest of the New World could be termed as a Crusade.
It is an interesting point, and one which has been explored in the past. One question which arose and was acknowledged in questioning as a good point was about the Treaty of Tordesillas. There must have been included among some primary sources discussion of calling this conquest a Crusade as Spanish conquistadors and royalty alike wished to prevent the double-entry into the New World by Britain and France.
Portuguese encroachment upon the perceived divine entitlement of Spain to the New World could be acknowledged as long as similar deferment to the superior naval capabilities of the Spanish Imperial Navy. Unfortunately, these other potential players who had not proven effective in the Middle East or in the Spice Islands yet, and had little bargaining position with which to enter the New World. Whether there will be an attempt to reclassify greater parts of the period of colonization in the New World as a crusade remains to be seen.