Sachs said he “immediately began to wonder if they were going to try to change the oath.” Since 1947, the law has required new citizens to swear an oath to the monarch and their successors. While the wording has changed on a few occasions since Queen Elizabeth’s reign began, young Canadians have been swearing by it for 70 years. That changed Thursday afternoon after her death. Sachs and dozens of others who attended a mock citizenship ceremony were among the first to pledge allegiance to the new monarch, King Charles III. “To be a part of that transition in such an abrupt way, it was truly a remarkable experience,” Sachs said. Immigration, Refugees and Citizenship Canada says that when a monarch dies, the oath changes to reflect the fact that Canada has a new sovereign. “The reference to Her Majesty in the Oath of Citizenship has been amended to refer to King Charles III. This change was made in accordance with the Interpretation Act and applies to all citizenship ceremonies going forward,” a department spokesperson told CBC News. A photograph of the late Queen Elizabeth II and current King Charles III standing on a balcony in London on June 5, the last of four days of celebrations to mark the Platinum Jubilee. (Hannah McKay/AP Photo) The announcement of the Queen’s death came about an hour before Sachs and the others were sworn in. Despite the short notice, Sachs said the ceremony went on “seamlessly”. Roberto Rocha, a journalist with the Foundation for Investigative Journalism and a former CBC journalist, reported seeing his friend swear in a series of tweets on Thursday. “The presiding judge reports the Queen now. She said the monarch is now King Charles III, King of Canada,” Rocha said in a tweet. Sachs said that, as an American taking Canadian citizenship, swearing an oath to a monarch felt “weird.” But he added that he had “always had a great admiration and affection for the Queen”. His ceremony ended with a touching tribute to Canada’s longest-serving monarch, when the person presiding over the oath added: “The queen is dead. God save the king” — which Sachs and the others echoed in unison. “It was a nice little coda to the oath itself,” he said.