Constantine was at Warsaw when the news arrived of the death of his brother.  The mother of Alexander was still living.  Even Nicholas either affected not to know, or did not know, that his wild, eccentric brother Constantine had renounced the throne in his favor, for he immediately, upon the news of the death of Alexander, summoned the imperial guard into the palace chapel, and, with them, took the oath of allegiance to his older brother, the Grand Duke Constantine.  On his return, his mother, who is represented as being quite frantic in her inconsolable grief, exclaimed,

“Nicholas, what have you done?  Do you not know that there is a document which names you presumptive heir?”

“If there be one,” Nicholas replied, “I do not know it, neither does any one else.  But this we all know, that our legitimate sovereign, after Alexander, is my brother Constantine.  We have therefore done our duty, come what may.”

Nicholas was persistent in his resolution not to take the crown until he received from his brother a confirmation of his renunciation of the throne.  Three weeks elapsed before this intelligence arrived.  It then came full and decisive, and Nicholas no longer hesitated, though the interval had revealed to him that fearful dangers were impending.  He was informed by several of his generals that a wide-spread conspiracy extended throughout the army in favor of a constitutional government.  Many of the officers and soldiers, in their wars against Napoleon and in their invasion of France, had become acquainted with those principles of popular liberty which were diffused throughout France, and which it was the object of the allies to crush.  Upon their return to Russia, the utter despotism of the tzar seemed more than ever hateful to them.  Several conspiracies had been organized for his assassination, and now the plan was formed to assassinate the whole imperial family, and introduce a republic.

Nicholas was seriously alarmed by the danger which threatened, though he was fully conscious that his only safety was to be found in courage and energy.  He accordingly made preparation for the administration of the oath of allegiance to the army.  “I shall soon,” said he, “be an emperor or a corpse.”  On the morning when the oath was to be administered, and when it was evident that the insurrection would break out, he said, “If I am emperor only for an hour, I will show that I am worthy of it.”

The morning of the 25th of December dawned upon St. Petersburg in tumult.  Bands of soldiers were parading the streets shouting, “Constantine for ever.”  The insurrection had assumed the most formidable aspect, for many who were not republicans, were led to believe that Nicholas was attempting to usurp the crown which, of right, belonged to Constantine.  Two generals, who had attempted to quell the movement, had already been massacred, and vast mobs, led by the well-armed regiments, were, from all quarters of the city, pressing toward the imperial palace.  Nicholas, who was then twenty-nine years of age, met the crisis with the energy of Napoleon.  Placing himself at the head of a small body of faithful guards, he rode to encounter his rebellious subjects in the stern strife of war.  Instead of meeting a mob of unarmed men, he found marshaled against him the best disciplined troops in his army.