The first nation-state in modern history was formed during the French revolution. After deposing of the King, the revolutionaries were facing threats from supporters of the old monarchical regime. To ward off the counter attack, they needed a large and powerful army.
Conscription made that possible. Soldiers were amassed from all parts of the First French Republic. The Jourdan Law of 1798 stipulated that “Any Frenchman is a soldier and owes himself to the defence of the Nation.” It demonstrates how conscription was essential to creating a national identity. In practice, up to 1,108,300 soldiers were recruited to the French army, making it the largest European army, which crushed the resistance to the revolution, and which enabled Napoleon Bonaparte to make huge territorial gains and change the old political order of Europe.