What is "strandhogg"

Strandhogg in old Norse was a Viking tactic consisting of a coastal raid with the intention of capturing livestock and indigenous peoples for the slave trade. A tactic enhanced by Viking longships' shallow draft.

The Vikings had already developed spy networks from their many commercial encounters with vicus. These spies informed them of the local customs, the dates of religious feasts, helped with translation and indicated places to plunder and personalities to be removed and held to ransom. It happened that Vikings made these raids against their own countrymen as well. Harald I, known as Harald Fairhair, prohibited strandhögg on the Norwegian territory.