Britain's Queen Elizabeth II canceled her participation in the traditional World War II commemoration in London on Sunday.
The reason for this is back problems, said the palace.
The date would have been the first official appearance of the 95-year-old since a hospital stay in October.
"After spraining her back, the Queen decided with great regret that she could not attend today's Remembrance Sunday ceremony at the Cenotaph (the central memorial, editor's note)," a statement said of the palace.
The queen was "disappointed," it said.
As the British news agency PA reported, citing unnamed sources, the sprain is said to have occurred only recently.
Accordingly, there were concerns as to whether traveling in the car and standing during the memorial ceremony for the fallen could affect recovery.
The Queen therefore remains in Windsor.
Worries about health
The monarch's rejection is likely to fuel worries about her health again.
After a hospital stay in October, she was given several weeks of rest.
The November memorial ceremony, however, is one of the royals' most important dates.
It was therefore firmly expected that the Queen would do everything possible to take part in the event in London's government district.
On Remembrance Sunday, which always takes place on the Sunday after the anniversary of the end of World War II on November 11, 1918, Great Britain pays tribute to its fallen soldiers.
The royals lay wreaths at the central memorial, the cenotaph.
Heir to the throne, Prince Charles (73), has been taking on this task for the Queen for several years.
But she wanted to attend the ceremony from a balcony in the nearby Foreign Ministry.