On February 18, 1853, Maximilian helped save the life of the young Emperor, foiling an assassination attempt by a tailor and former Hussar, János Libényi, a Hungarian nationalist.
The Emperor was taking a stroll with Count Maximilian O’Donnell on a city-bastion, inside Vienna, and at about 1 pm.
At the moment he looked over the parapet to review an exercise of troops, Libényi approached and struck the Emperor in the neck from behind with a knife.
Even though the Emperor was wounded and bleeding, his collar may have helped save his life.
Maximilian Graf O'Donnell struck Libényi down with his sabre.
Another witness who happened to be nearby, the butcher Joseph Ettenreich, quickly overwhelmed Libényi.
For this deed, he was later elevated to nobility by the Emperor and became Joseph von Ettenreich.
Libényi was subsequently put on trial and condemned to death for attempted regicide.
He was executed near the Spinnerin am Kreuz in the Favoriten-district.

After the unsuccessful attack the Emperor's brother Ferdinand Maximilian Joseph, the later Emperor of Mexico, called upon the Europe's royal families for donations to construct a new church on the site of the attack.
 The church was to be a votive offering for the rescue of the Emperor.
It is located on Ringstraße in the district of Alsergrund close to the University of Vienna, and is known as the Votivkirche.
On February 18, 1853, Maximilian helped save the life of the young Emperor, foiling an assassination attempt by a tailor and former Hussar, János Libényi, a Hungarian nationalist. The Emperor was taking a stroll with Count Maximilian O’Donnell on a city-bastion, inside Vienna, and at about 1 pm. At the moment he looked over the parapet to review an exercise of troops, Libényi approached and struck the Emperor in the neck from behind with a knife. Even though the Emperor was wounded and bleeding, his collar may have helped save his life. Maximilian Graf O'Donnell struck Libényi down with his sabre. Another witness who happened to be nearby, the butcher Joseph Ettenreich, quickly overwhelmed Libényi. For this deed, he was later elevated to nobility by the Emperor and became Joseph von Ettenreich. Libényi was subsequently put on trial and condemned to death for attempted regicide. He was executed near the Spinnerin am Kreuz in the Favoriten-district.
After the unsuccessful attack the Emperor's brother Ferdinand Maximilian Joseph, the later Emperor of Mexico, called upon the Europe's royal families for donations to construct a new church on the site of the attack.  The church was to be a votive offering for the rescue of the Emperor. It is located on Ringstraße in the district of Alsergrund close to the University of Vienna, and is known as the Votivkirche.
Maximilian Karl Lamoral O'Donnell