Why was sir Richard lionhearted held prisoner at the kaiserburg castle?

Sir Richard the Lionheart was held prisoner at Kaiserburg Castle in 1192 because he was captured by Duke Leopold of Austria during his return from the Third Crusade. After being handed over to the Holy Roman Emperor Henry VI, he was imprisoned in exchange for a substantial ransom. The Emperor sought to capitalize on Richard's capture to assert his power and gain wealth. Ultimately, Richard's imprisonment became a political tool, reflecting the complex dynamics of power among European monarchs at the time.