European monarchies feared the Revolution and were concerned for the French royal family. Royal intermarriage made intervention a matter of helping relatives as well as honouring alliances. A declaration threatening intervention did not halt the Revolution, and France chose to declare war on Austria rather than wait for an Austrian attack. Prussia joined its ally, the invading army captured Verdun, and the advance helped trigger the September Massacres before a French counterattack and the proclamation of the Republic. Britain entered reluctantly but remained at war after most of its coalition partners had left.
Chapter · 36:13-42:28
How revolution escalated into coalition war
Dynastic alarm, French declarations of war, invasion, and revolutionary counterattack expanded the crisis into the War of the First Coalition.