By the 16th Century they were rapidly becoming the greatest power in Northern Europe, and during the Thirty Years War the Swedish Army definitely kicked some tail. (We also recall that earlier the Swedish Army set up the Swedish Empire).
I'm not sure today's Viking descendants would agree with you that the Vikings had actually been defeated or that such action was really necessary!
Two out of the last three major leaders of Russia/USSR have been obvious Viking descendants ~ Gorbachov and Putin. Yeltsin was obviously of Slavic "Great Russian" descent.
The last 42 US Presidents have clearly had Viking ancestry (most of them quite provable), and ALL the kings and queens of England since the 11th century have had Viking blood.
You Greek perhaps? Western European people today have no fear of Vikings and look back proudly at their rugged and resourceful ancestors who plundered the world with tiny boats.
No, I’m not Greek. By defeating the Vikings, I mean ending the Viking raids that terrified Europe. This was not accomplished through force of arms on a battlefield (although Harold II of England did defeat a Viking invasion from Norway in 1066). Rather, it was accomplished through evangelism- the Norse people were converted to Christianity. Their conversion coincided with the end of those Viking raids. After that, the Norse became more involved in trade and commerce. The Hanseatic League is a good example.
You would probably be interested to know that the 1st Crusade was roughly one third Greek or Byzantine and one third Frankish (men from the Frankish successor states of France and the Holy Roman Empire). The rest came from areas controlled by the Norse, making nearly a third of the entire Crusade Viking.