German Emperor Henreich VI extorted the Romans in 1187 with the threat of invasion. Alexios Angelos agreed to pay “5,000 lbs of gold.”

German Emperor Henreich VI extorted the Romans in 1187 with the threat of invasion. Alexios Angelos agreed to pay “5,000 lbs of gold.” Alexios had to issue a new tax to raise funds. He assembled the people of Constantinople in the Hippodrome & proposed it, and they refused

This tax was called the Alamanikon, the “German tax.” However, “when he convened an assembly of the populace to explain it, it was vehemently shouted down, and he repudiated the idea.” The people of Constantinople essentially vetoed the policy, this shows how much influence the people of Constantinople had over the imperial office, and how different it functioned to be the Roman Emperor compared to being a king in Western Europe.

Fortunately for the Romans, Heinreich died in 1197 before he could collect his extorted treasure. This temporarily removed the threat, but the harsh reality was plain and clear - “Constantinople could now be bullied and intimidated.” The fact they agreed to pay this humiliating sum to the German Emperor was very likely fuel for the fire when it came to those who would soon after use a crusade to lead an army to the Bosphorus and demand their own huge sum - and indeed take every piece of removable wealth from Constantinople and leave it in smoldering ruins. 

Agreeing to this could very well be a pivotal moment on the Roman side which led to their downfall, it was a tangible sign of weakness to westerners. Niketas Choniates certainly saw it that way - he looked back and wrote that “all of this prefigured the ‘oppressive slavery that would soon be imposed by the west on our entire race.’”

Source - The New Roman Empire: A History of Byzantium