It was the year 1345 that the Dutch (Hollanders) attacked the Frisians at Starum by sea with an army of 85.000 men, led by Willem van Henegrouwen (IV) and Jan van Beaumont (uncle of Willem). They wanted to take over Starum. When they attacked they put the towns Laaksum and Warns on fire, but the Frisian fought back. The Frisians defeated the Dutch and only a small part of the Dutchmen made it back to Amsterdam. Also Willem van Henegrouwen died in battle.
This battle became a symbol for the Frisian freedom. Still, each year a memorial takes place.
On the big boulder you see above the text is written: Leaver dea as slaef (Rather dead than slave)