In 734 a Frankish army commanded by
Majordomo Charles Martel invaded Friesland in a campaign that was part of a series of ongoing wars and skirmishes between the Franks and the Frisians. Marching along the river Boarn the Frankish army reached the mouth of the river where it used to flow into the Bordine estuary or
Middelsee. This estuary has since silted up and was claimed for agriculture during the 10th to 14th century. The Frisians commanded by King
Poppo used boats to land their army in
Jirnsum and surprise the Franks. However, the Frisian army was beaten and Poppo killed. The Franks gained control of the Frisian lands west of the
Lauwers estuary and the Frisians became vassals of the Franks apart from the tribes living in
East Frisia in present-day
Germany. ==References==