On the night of November 25, 1741, Anna Leopoldovna woke up to the noise and clatter of soldiers' boots. Enemies had come for her and her family. In the "Brief Report" by Shetardi, it is recounted that upon seeing Elizabeth and the soldiers, "the ruler, seized with terror, obeyed her orders, begging not to give the command to commit violence against her and her family." Prince Anton Ulrich was not allowed to dress and was carried half-naked wrapped in a sheet (in other sources, either a blanket or a fur coat) to the sleigh. During the "arrest" of the one-year-old emperor, there was a delay. According to Korf's version, the soldiers were given strict orders not to make noise and to take the child only when he woke up. So for about an hour, they stood silently by the cradle until the boy opened his eyes and cried out of fear at the sight of the fierce faces of the grenadiers. Moreover, in the chaos of gathering, the emperor's four-month-old sister, Princess Catherine, was dropped on the floor in the bedroom. It was later discovered that because of this, she lost her hearing. But no one paid attention to this — little Catherine turned out to be the only victim of Elizabeth's bloodless revolution.

Every step of the family was closely monitored. Any cry of Ivan Antonovich's baby was detailed in reports: “Playing with the dog, he hits it on the forehead, and when asked: ‘To whom, father, will you cut off the head?’ — he answers that it will be to Vasily Fedorovich Saltykov.” The guards also reported on each other.

On January 2, 1743, the prisoners and their guards were moved to a new place of confinement. The fortress ("Dinamantschanets") resembled the Peter and Paul or Shlisselburg fortresses, was surrounded by water, and was quite suitable for isolating dangerous detainees. From there, Anton Ulrich could no longer send messages to the outside world. The conditions of detention were tightened, and hopes for a possible departure collapsed. "Since my arrival at Dinamintschantz, the sea gates have been locked tight, and the keys to those gates are always with me. Only the Riga gate remains open for passage, and beyond the garrison guard, a guard stands at those gates," reported Saltykov. The Empress's decree categorically forbade allowing anyone to visit the prisoners or deliver letters and other items "under the pretext that something was sent to Julie from her mother, be it food or anything else."

On December 3, 1742, the Brunswick family was relocated to Dünamünde. In January 1744, an order followed to move them to Ranenburg, and they were almost taken to Orenburg because Captain-Lieutenant of the Guards Vymdonsky, who was entrusted with the transportation, mistook Ranenburg for Orenburg. When the family members were informed about the move to Ranenburg and that they would be seated separately in different carts—husband, wife, and children—they cried for a quarter of an hour but did not show any sign of anger.

Formally, he reigned during the first year of his life under the regency of first Biron, and then his own mother Anna Leopoldovna. The infant emperor was overthrown by Elizabeth Petrovna, spent almost his entire life in solitary confinement, and was killed by guards at the age of 23 during the reign of Catherine II while an attempt was made to free him.

Anton Ulrich never received even a little freedom, nor a breath of fresh air, nor did the affairs of Empress Catherine take a favorable turn for him. By the age of sixty, he had become feeble, began to go blind, and after spending 34 years in captivity, he died on May 4, 1776. As he was dying, he asked that his children be given "at least a small measure of freedom."

Letter from the city professor Olof Worm to Mr. Jiorvel, librarian to the Swedish king in Stockholm,

Torn from their familiar surroundings, surrounded by strangers speaking a foreign language, the princes and princesses were unhappy and clung to each other. The aunt-queen settled them in the small town of Horsens in Jutland; she wrote to Catherine: "I will try to gild their chains," to introduce them to the lifestyle of the Danish court. But these were only words; the queen never once wished to see her nephews and nieces. Their small court existed from 1780 to 1807 and initially consisted of four brothers and sisters and their court staff. It lasted until 1807, when Princess Catherine, the last of the exiles, died at the age of 66. These four princes and princesses were: Catherine, born in 1741; Elizabeth, born in 1744; Peter, born in 1745; and Alexei, born in 1746.

Anyone who has ever walked along Petrovskaya Street in Kronstadt has seen the building with a huge stained-glass window in the Art Nouveau style. This is the former machine school of the Baltic Fleet; it housed the stokers' school, and inside the building there was a working model of a military ship's stoker room, a machine school, and a marine technical college.