The French revolutionary wars of 1791-92 were due to the attack on France by Austria, Prussia and Britain. These three countries were monarchies. They feared that if they did not attack France and suppress the French revolution, then the revolution would spread to these countries as well and threaten the existing monarchies. Hence, they decided to launch wars on France to end the French revolution and restore Louis XVI to the French throne.
The revolutionary wars ultimately led to the execution of Louis XVI in 1793. He was accused and convicted by the French revolutionary government of conspiring with foreign powers against France.