King Charles laid a wreath in memory of the victims of the allied bombing in World War Two during a visit to Hamburg's St Nikolai memorial, the remains of a church in Germany's northern port city severely damaged by the air raids.
The gesture comes on the last day of Charles' three-day tour of Germany, his first overseas state trip since ascending the British throne last year designed to strengthen bilateral and European ties.
It comes shortly before the 80th anniversary of the allied bombing of Hamburg in July known as "Operation Gomorrah" that killed some 40,000 people and destroyed swathes of the city.
In response to Nazi air raids on civilian targets in Poland and later London, the Allies dropped about 1.9 million tonnes of bombs on Germany in an effort to cripple German industry. The allied raids killed some 500,000 people.
Earlier, Charles also paid his respects at the memorial to the Kindertransporte, a rescue mission that allowed some 10,000 Jewish children to flee Nazi-occupied Europe in the late 1930, mostly to Britain.
"Heeding the lessons of the past is our sacred responsibility, but it can only be fully discharged through a commitment to our shared future," Charles said in a bilingual address to the Bundestag lower house of parliament on Thursday.
"Together we must be vigilant against threats to our values and freedoms, and resolute in our determination to confront them."
Later on Friday, Charles, who succeeded his mother Queen Elizabeth when she died in September, is set to learn more about the port of Hamburg's adoption of green technologies and to meet representatives of some of the firms involved.
"Our countries are both accelerating the expansion of our hydrogen economies, the fuel which could transform our future," he told the Bundestag. "I am looking forward to seeing Hamburg’s plans to use hydrogen in its efforts to become a fully sustainable port."
Throughout his visit, German officials have praised his interest in environmental causes and sustainability that has shone through in the engagements he has chosen to undertake.
"I have great respect for his decades-long commitment to the protection of the environment and climate," tweeted German Chancellor Olaf Scholz, designated the "climate chancellor" during his election campaign in 2021.
(Reporting by Phil Noble and Maria Martinez; Writing by Sarah Marsh; editing by Matthias Williams, William Maclean)
