On the morning of that day, Count O'Donnel, the Vice-Governor of Milan, announced the Emperor's concessions. Before night he was the hostage of the revolution, signing whatever decrees were demanded of him till in a few hours even his signature was dispensed with. The Milanese had begun their historic struggle.
Taking refuge in the Citadel, Radetsky wrote to the Podestà, Count Gabrio Casati (brother of Teresa Confalonieri), that he acknowledged no authority at Milan except his own and that of his soldiers. Those who resisted would be guilty of high treason. If arguments did not avail, he would make use of all the means placed in his hands by an army of 100,000 men to bring the rebel city to obedience. Unhappily for Radetsky, there were not any such 100,000 men in Italy, though long before this he had told Metternich that he could not guarantee the safety of Lombardy with less than 150,000. In spite of partial reinforcements, the number did not amount to more than from 72,000 to 75,000, while at Milan it stood at between 15,000 and 20,000. But if we take the lower estimate, 15,000 regular troops under such a commander, who, most rare in similar emergencies, knew his own mind, and had no thought except the recovery of the town for his Sovereign, constituted a formidable force against a civilian population, which began the fight with only a few hundred fowling-pieces. The odds on the side of Austria were tremendous.
If the Milan revolt had been one of the customary revolutions, arranged with the help of pen and paper, its first day would have been certainly its last. But even more than the Sicilian Vespers, it was the unpremeditated, irresistible act of a people sick of being slaves. At the beginning Casati tried to restrain it; so, with equal or still stronger endeavours, did the republican Carlo Cattaneo, whose influence was great. 'You have no arms,' he said again and again. Not a single man of weight took upon himself the awful responsibility of urging the unarmed masses upon so desperate an enterprise; but when the die was cast none held back. Initiated by the populace, the revolt was led to its victorious close by the nerve and ability of the influential men who directed its course.