912–922: Reign of Æthelflæd, queen of Mercia. She commanded armies, fortified towns, and defeated the Danes. She also defeated the Welsh and forced them to pay tribute to her.[27] 934: Queen Emma of France dies during a military campaign in which she helped her spouse against his vassals: she was an active army leader. [citation needed] 968: Olga of Kiev defends her city during the Siege of Kiev (968).[citation needed] 971: Sviatoslav I of Kiev attacked the Byzantine Empire in Bulgaria in 971.