Complex sentence: In 1309, together with Jan Breydel and Jan Heem, he led a new uprising in Bruges, this time against the adverse effects (for Flanders) of the peace of Athis-sur-Orge (1305).
Split into simpler sentences: In 1309, together with Jan Breydel and Jan Heem, he led an uprising in Bruges. This to counter the negative consequences of the peace of Athis-sur-Orge (1305).