When we talk about human sacrifices, people usually link that to an image of deep jungles somewhere in the southern areas of South America, and those semi-naked indigenous (or perhaps the Incas and Aztecs) opening someone's chest and taking out the heart, while the victim succumbs to death. But sacrificing humans to the gods or to achieve something good to the community, has always been a common practice among the cultures of Europe, far back from the Chalcolithic and Bronze Age to the medieval Ages, and in some places later than that.
It may be common knowledge that in the northern european societies, (before and during the Viking Age) human sacrifices were common, and even great chieftains and kings would sacrifice themselves for their army to achieve victory.
There is an interesting place that I would like to mention here (and that is actually the main subject of this post) that was the background for human sacrifices in northern Europe. Trelleborg – in modern Sweden – it was found there, by the archaeologists, the remains of sacrificed animals and humans. Interestingly, the site contains the remains of children as well, between the ages of four and eight. The remains have been found buried within deep wells. The remains of these children indicate the importance of human sacrifice in Scandinavian culture. If the Vikings sacrificed their own progeny, then human sacrifice must have been of the utmost importance in their rituals.
Northern mythology tells us of Odin sacrificing his eye in the well of Mimir in order to attain knowledge and be able to see into the past, present and future; this mythic well may represent the vessel in which offerings and sacrifices are thrown to the gods.