Also present were several members of the armed forces, including Army Col. Greg Gadson, a double amputee who sustained his injuries in Iraq in 2007, according to the pool report.
Prince Harry read from prepared remarks at the embassy event, thanking people for their support of the HALO Trust, which is celebrating its 25th anniversary.
He thanked the American government for its support.
"The US Government is by far the largest donor to humanitarian mine action worldwide. This started in earnest in the 1990’s and was reinforced by President Clinton’s ten year initiative. American governmental support has been enormously generous and very well sustained," he said.
He also said his mother, the late Princess Diana, would be "so proud" of his work with HALO. Prince Harry is a patron of the charity group and Diana was also a supporter of the organization.
"My mother, who believed passionately in this cause, would be proud of my association with HALO. In her special way, she adopted it as her own. She would join me – along with all of you, I’m sure – in praising HALO for the amazing work that it has done over the past quarter century, and in hoping that one day soon its humanitarian work will be done," he said.
The prince dined between Lady Westmacott, the wife of British Ambassador Sir Peter Westmacott, and Teresa Heinz, the wife of Secretary of State John Kerry.
Scallops, veal, and pudding was served.
On Friday, Prince Harry will visit Arlington National Cemetery, where he will lay wreaths in Section 60 and at the Tomb of the Unknown Soldier. He will then visit wounded service members at Walter Reed National Military Medical Center. He will also make stops in Colorado, New Jersey, New York and Connecticut during his week-long visit.
-- This story was updated at 8:52 a.m. on May 10.