This one pendant does not by itself show an army's first steps.
Debated. Specialists think a person with the Viking army that arrived in AD 865 wore it.
It was found at Elsing, near Dereham, in Norfolk, England. It is about 20 millimetres across. It copies a gold coin of Emperor Louis the Pious, first minted around AD 816, but this piece is a later copy made on the Continent. It was pierced twice so it could be worn, likely with the portrait facing out. The page says 22 copies of this kind are known in Britain, and that together they are used to plot the army's route.
Whether this single coin marks those first steps is still only a suggestion.
https://www.ancient-origins.net/news-history-archaeology/viking-gold-pendant-00102554