What were the 2 or 3 of most impactful Crusades of all 8 crusades (in terms of RC Church policy and ‘international stability’? The first and fourth?. I’m really talking about how these crusades shaped the world at the time.
The first certainly,followed by the fourth and the third.
After the third you have a dead Emperor, the first step of the Teutonic, Cyprus in catholic hands, a concession for free access to Jerusalem, and a captive king of England (and a lovable rogue in Sherwood’s forest…)
I concur on the 4th. After what the Crusaders did, it was a matter of time before the Eastern Roman Empire fell.
I assume we’re just considering the numbered Holy Land Crusades here, not any others. In which case yes, the First and Fourth, definitely, and you could make a case for the (negative to Christendom) impact of the Second over the Third.
Do serious scholars view the 'German Crusade" of 1197-98 following the Third Crusade as a real Crusade?
What’s a “real” Crusade?
The Emperor’s Crusade featured a bunch of armed Christians fighting to claim territory in the Levant from Muslim occupiers. That’s as real a Crusade as any other.
The numbering system is an arbitrary, fairly recent invention, the medieval scholars certainly didn’t use it.
If the preservation/destruction of the ERE is a criteria (and it obviously is) then the First Crusade is streets ahead of all the others in importance.
When Alexios Komnenus sent ambassadors to Rome to ask for the Pope’s assistance in recruiting mercenaries, it was because he felt under direct threat. Byzantium had lost much of Asia Minor and didn’t have the manpower to take on the Turks in battle or to hold a defensive line.
The arrival of the Crusader armies changed all that. In the wake of the victorious Franks, Normans et al, Komnenus and his successors were able to restore the Empire’s territory, finances and military capability - if not to its absolute peak, then at least to something pretty substantial. (Which is why it was worth looting so drastically in 1204).
Had it not been for the intervention of the First Crusade and for the subsequent establishment of the Crusader States the Turks would have been well able to reduce and probably conquer Byzantium long before they actually did.