LONDON – In a meeting symbolizing the end of years of enmity between British rule and Northern Ireland republicans, Queen Elizabeth II shook hands Wednesday with a former Irish Republican Army commander.

Martin McGuinness, now a deputy first minister of Northern Ireland and a member of the pro-republican Sinn Fein party, was a senior IRA member in the years of sectarian violence. During that time, the group was responsible for blowing up the yacht of Lord Louis Mountbatten, the queen’s cousin, killing him and three others while they vacationed off the coast of Northern Ireland in 1979.

The once unthinkable handshake took place behind closed doors at a charity arts event in Belfast, witnessed by the queen’s husband, Prince Philip, and leading politicians including Irish President Michael Higgins and Northern Ireland’s first minister, Peter Robinson.

The seemingly mundane greeting was widely heralded as a turning point. Peter Sheridan, host of the event, told reporters, “It’s a huge act of reconciliation; you cannot underestimate how important this is.”

The queen, wearing a pale green coat and hat, also toured a local art exhibit, the work of a cultural charity aimed at fostering cross-community relations between Catholics and Protestants. As she left the Lyric Theatre, the carefully chosen apolitical context where the event took place, the queen smiled as she shook hands again with McGuinness, this time with a camera crew filming, as he was standing in line with other officials.

Afterward, McGuinness told reporters he spoke to the queen in Gaelic, explaining to her his words meant “Goodbye and God speed.”

Some hard-line republicans view McGuinness as a traitor, but most agreed that it was a step forward.

“From the queen’s point of view, she lost a member of the family, so it’s a big step for her,” Joe McGowan, a Northern Ireland historian, told Sky News. “Martin McGuinness is conceding something. He has to recognize that the struggle over the past 30 years was lost, in a military sense anyway.”