It said: "Princess Alice personally saw to it that the members of the persecuted Jewish family had everything they needed, and even visited them in their hiding place, spending many hours in their company."
Thanks to her, the Cohen family survived and today lives in France, it said.
The princess died in 1969 and in 1988 her remains were brought to Jerusalem.In a private 1994 visit to Yad Vashem, Prince Philip, the Duke of Edinburgh, planted a tree there in his mother's honour.
Yad Vashem Chairman Avner Shalev is guiding Prince William through the memorial's exhibitions detailing the death of 6 million Jews systematically killed by Nazi Germany and its collaborators during World War II.
After the visit, Benjamin Netanyahu and his wife Sara hosted the Prince at the prime minister's residence.
Though the trip is being billed as non-political, and places a special emphasis on technology and joint Israeli-Arab projects, William is also meeting with Israeli and Palestinian leaders, and visiting landmark Jerusalem sites at the heart of the century-old conflict.
Three decades of British rule between the two world wars helped establish some of the fault lines of today's Israeli-Palestinian conflict, and Britain's withdrawal in 1948 led to the eventual establishment of Israel and Jordan.
Britain has since taken a back seat to the United States in mediating peace efforts, and the royal family has mostly steered clear of the region's toxic politics.
For the 36-year-old William, second in line to the throne, it marks a high-profile visit that could burnish his international credentials.
- AP