Passage: The first session was held on 20 September 1792. The following day, the assembly agreed the proposition "That royalty be abolished in France" and was carried with cheers. On the 22nd came the news of the Battle of Valmy. On the same day it was decreed that "in future the acts of the assembly shall be dated First Year of the French Republic". Three days later the corollary that "the French republic is one and indivisible" was added to guard against federalism. A republic had been proclaimed, but it remained to enact a republican government. The country was little more republican in feeling or practice than it had been before at any time since Varennes. But now it had to become a republic, because it no longer had a king.When the Convention met the military situation was undergoing an extraordinary transformation that seemed to confirm the Girondin prophecies of easy victory. After Valmy the Prussians withdrew to the frontier, and in November French troops occupied the left bank of the Rhine. The Austrians, who had besieged Lille in October, were defeated by Dumouriez at the Battle of Jemappes on 6 November and evacuated the Austrian Netherlands. Nice was occupied and Savoy proclaimed its union with France. These successes made it safe to quarrel at home.

Question: When was decided to end royalty?
20 September 1792