Thats disputable -- I'd put it in the top 3 yes, along with the Crimean War and the Siege of Vienna
in MY mind the worst was the Crimean war -- willingly two major Christian powers allied themselves with a Moslem power against a Christian power. That was utterly despicable.
I think that war, the Crimean war was started over the issue of the Church of the Nativity of Jesus, the site where Jesus was born. This is the shrine where the “star” is located.