About “Oaths of Strasbourg”
The Oaths of Strasbourg were a military pact signed on 14 February 842 by Charles the Bald and Louis the German. They made this agreement against their older brother Lothair I, who was the designated heir of Louis the Pious, the successor of Charlemagne. A year later, the Treaty of Verdun was signed, which had significant effects on the political map of Western Europe. (Summary adapted from Wikipedia, CC BY-SA 4.0.)
Some summaries adapted from Wikipedia, CC BY-SA 4.0.