"It is with great sadness today that this publication reports the death of the most monumental figure in European Civilization. Yesterday, at his home in Paris, Caesar Napoleon I passed into the arms of the Heavenly Father at the age of 66. Born on August 15th, 1769, to a Corsican family of minor nobility, Caesar, christened at birth as Napoleone di Buonaparte, attended the famed École Militaire in Paris. After serving a short time in the French Royal Navy, Napoleon became more interested in artillery, and from there out, his story is well known by all the world."
-Lyons Gazette, January 5th, 1835
"At his death, he was comforted by his wife, Her Imperial Highness, Caesarina Marie Louise, his son, Emperor Napoleon of Spain, his younger brother Jerome, several of his closest private friends, and his dear friend French Prime Minister Michel Ney. The cause of his death is not yet confirmed, but it is widely assumed that it was a combination of bronchitis, stomach ulcers, and a heart condition."
-Imperial Times (Paris), January 5th, 1835
"The French Ministry of Public Affairs states that, due to his declining condition being well known as of late, other nations already had sent ambassadors to give their best to the Imperial Family during this time of sorrow. England's King Edward was, ironically, the first to send such an emissary."
-Rheinbund Allgemeine Zeitung (Confederation of the Rhine General Newspaper), January 7th, 1835
"The French Embassy in Copenhagen claims Napoleon of Spain, "L'Aiglon," is to take the French Crown next month. There is much excitement amidst the sorrow as to how the 24 year-old Caesar Napoleon II will rule. Speculation is also rampant that the young monarch will form an official union between France and Spain."
-Berlingske Tidende (Berling's Times) (Copenhagen), January 11th, 1835
"Rumors swirl of assassination by poison being the cause of Caesar Napoleon I's death. While these have not been at all substantiated, this version of events allegedly originated with a servant at the Imperial Palace."
-London Times, January 13th, 1835
"Accusations of the Corsican being poisoned has interrupted the planned coronation festivities (scheduled for February 18th), and Napoleon II is apparently taking these theories seriously enough to be fearing for his own life. Security for the coronation has been tripled."
-Berlin Zeitung, January 20th, 1835
As seen in the newspaper excerpts above, there was a witch-hunt going on in Paris in mid-January to stamp out an alleged conspiracy to take the lives of the Imperial Family. The coroners were reporting that Napoleon I had showed symptoms of arsenic poisoning. Questions immediately arose as to who would do such a thing, with many suspecting a member of his inner circle, perhaps a general or marshal wanting to attempt a coup. Servants at the Imperial Palace were thoroughly interrogated, and a few were held as suspects. Chief among them was 31 year-old former Grand Army drummer Wilhelm Lukas Hofmeister, one of Caesar's chief butlers and servants.
Wilhelm Lukas Hofmeister, anarchist assassin of Caesar Napoleon I (Paris Police Sketch, 1835)
On January 21st, Hofmeister, an ethnic Hessian, was arrested by Paris Police. They gutted his small house on the Imperial Palace grounds for evidence and found nothing too incriminating. Just as it looked like he would walk free, a sharp-eyed constable spotted a shovel next to the house had fresh dirt and footprints around it. The officer grabbed the shovel, followed the prints, and discovered recently disturbed earth. He started digging and quickly came up with three bottles of arsenic, several medical books on poison, and a large tome entitled "The Anarchist Way," by Meinrad Beutel, a prominent riot-inciter in the Confederation of the Rhine. By the next day, all known anarchists in Paris had been imprisoned. Ethnic Hessians were also put under surveillance by the secret police. Several dozen suspected anarchists were lynched and murdered across Europe as the news spread. Even in countries rival to France, the murder of a monarch was unsettling.
Hofmeister refused to confess, discuss possible members of a cell, or even talk to authorities, knowing he would be executed anyway. The police swiftly turned to torture, but still, they could not get any information. Jourdain Roux, lead investigator into the plot, wrote in his diary on January 24th, "The Hessian cretin refuses to break. He withstands every measure we use against him. He must break. I must break him. The Empire is not safe until he talks." The next day, following brutal torture, Hofmeister died in custody. But while he was dying, he screamed something deliriously about "rooftops."
Immediately, the Paris Police and the French Army started a massive sweep of all the rooftops in the city.
THE CORONATION OF NAPOLEON II
Caesar Napoleon II in His Study
(by Thomas Sylvestre Lestrange, 1835)
On February 18th, 1835, Napoleon II (Napoleon I of Spain), at age 24, became the youngest most powerful man since Alexander the Great. Despite the assassination plot, he was determined to press onward with the huge planned festivities. While the fears of everyone involved would call for a shorter, quicker event, the coronation would be very public. Napoleon II, dashingly handsome in his blue uniform, made the carriage ride from the Palace to Notre Dame Cathedral amidst a a sea of admirers. Upon getting out in front of the same church his father was crowned at decades before, many held their breath, as if at any time a crazed anarchist might leap out and knife him through the heart. Fortunately, he made it inside without problem. As he received blessings from Pope Gregory XVI at the altar upon which sat his multiple crowns, a man named Tristan Langlais was taking a position in across the street. A private in the army, the assassin hardly looked like an anarchist, and everyone was fully aware he was "standing guard" there, along with several dozen other (perfectly loyal) soldiers.
Bear in mind that at this point Napoleon II was merely a womanizer, and as of then had yet to acquire a bride and heir. If Napoleon II died, it would be a catastrophic event, likely with a massive European civil war.
During the next fifty minutes, Napoleon II was crowned with the old crowns of France, Andorra, Italy, as well as the new one of the United Empire of Brazil and Argentina. He was then proclaimed to legally and rightfully be: "
His Imperial and Royal Majesty Napoleon II, By the Grace of God and the Constitutions of the Republic, Caesar of the French and Spanish, Emperor of Brazil and Argentina, King of Italy, King of Andorra, Lord of Mann, Mediator of the Helvetic Confederation, Protector of the Confederation of the Rhine, Protector of the Free City of Lisbon, and Duke of Reichstadt." The title of "Prince of Bombay" was proclaimed to be a dauphin-like position for the heirs to the French throne, and as such, would be temporarily unused until a son or daughter had been born.
When the ceremony was over, Caesar Napoleon II walked out the doors of Notre Dame under heavy guard, with tens of thousands screaming his name and singing the national anthems of the various empires and kingdoms involved. Flags fluttered in the winter wind, fists went up and down, trumpets blared, and shouts of "Long Live the Emperor!" were chanted in a dozen languages. As he was about ten paces from his carriage, Private Langlais, hiding his doings from the other guards by standing behind crates on the flat roof of the building across the street, raised his rifled musket to his shoulder, took aim, and squeezed the trigger.
This was a now-or-never moment for European History. If the bullet missed or merely wounded Napoleon II, the new Caesar would likely make it his personal vendetta to destroy anarchism and non-conformism in all its shapes and sizes. If it killed him, Europe would indeed likely be engulfed in anarchy and warring states trying to grab up whatever they could from the decapitated corpse of France. Truly, the fate of mankind might well have been said to be riding on that
Single Bullet.
Smack.
Screams.
Shouts.
Gunshots.
People fell.
People fled.
The bullet had lodged itself in the right leg of Napoleon II, sending him flying down the cathedral steps in all his regalia. Guards panicked everywhere, but one lucky officer had seen the puff of gun-barrel smoke and flash over the noise and lights of the coronation crowds. It was Detective Jourdain Roux, the man who had broken Hofmeister. Roux dispatched soldiers to barricade the building across the street, and as Langlais attempted to escape by leaping across to a neighboring rooftop, the Imperial Guardsmen opened fire and riddled him with bullets. The anarchist's corpse came crashing to the cobbled ground three stories below. A note in his pocket revealed he had expected death, and the paper simply said, "I die for Freedom."
Back at the church steps, Napoleon II was alive and well (and cursing loudly and profanely) as his assistants and officers heaved him into his carriage and took off for the Palace. Weeping and screaming citizens were barely able to get out of the way as the Imperial Family's carriage caravan sped at break-neck pace to safety. At this point, security officers and police worried about a widespread "killbox," with gunmen and perhaps even grenadiers waiting to murder everyone in the government. As soon as the Imperial Palace's gates closed behind them and Caesar was rushed to his personal doctors, the whole city was put on lockdown.
Napoleon II makes his escape (1835 London Times illustration)
No one went in or out of Paris for days without written approval by the government. The Imperial Guard and Paris Police did massive sweeps, going house to house, making mass arrests, seizing property, and practicing brutality on those who did not cooperate. Patriotic fervor hadn't been as high since the last coronation, and many militias roamed the streets, looking for anyone affiliated with opposition to the Empire or its leaders. The days after the Coronation Plot, as it came to be called, are widely considered to be the foundation upon which later European totalitarianism was built.
Note: Yes, I am taking preemptive measures to make sure political opponents of the European establishment are branded traitors and anarchists. I believe, in just these two chapters, I've largely aborted anything on the level of OTL 1848. That means little advancement for republican-democracy. The butterfly effects from this are innumerable.
EDIT: And yes, you could wonder/propose in-universe conspiracy theories about the whole "Caesar Napoleon was poisoned" thing. I'll leave that to the readers, though.