Belgian King Albert II abdicated on Sunday in an emotional ceremony that cleared the way for his eldest son, Prince Philippe, to ascend to the throne.

“Philippe, you have all the qualities of heart and intelligence to serve our country well in your new responsibilities,” King Albert told his heir. “You and your dear wife Mathilde have all of our trust.” King Albert also paid tribute to his spouse, Queen Paola, thanking her for her support over his 20-year reign and sending her “a big kiss.” He later embraced his son, bringing tears to Mathilde’s eyes.

The 79-year-old relinquished the throne in a concession to his age and health. It is the first time that Belgium sees a king abdicate willingly in the 182-year history of its monarchy.

Prince Philippe, 53, is the country’s seventh king. His ascension to the throne was set to be formalized at noon (1000 GMT) with an oath before parliament.

The father of four will swear to observe the Belgian constitution and “preserve national independence and the integrity of the territory.” The royal family is seen as one of the few forces uniting the European country’s fractious Dutch-speaking Flemish and French-speaking Walloon communities.

Albert this week has repeatedly urged the country to stay united.

“My last recommendations to all of you assembled here are to work without rest on the cohesion of Belgium,” he told those attending his abdication ceremony.

“This way, you will be even more architects of peace ... Our country will be an inspiration for Europe, which seeks unity in diversity.” The king is a key player in the formation of Belgium’s governments, serving also as its head of state and the commander-in-chief of its armed forces.

King Albert paid tribute to Prime Minister Elio Di Rupo and the country’s other politicians for all they have achieved. Mr. Di Rupo has been in power since 2011, after Albert helped end a political standoff that left the country without a government for 535 days.

Mr. Di Rupo told the outgoing king: “It’s with a head held high and a duty perfectly accomplished that you today turn an important page in the history of our country.” The festivities were set to continue Sunday with cannon shots after Philippe completes his oath, a military parade and a fireworks display. The royal family is also due to greet the crowds from the balcony of their Brussels palace.

The celebration coincides with the country’s National Day.

King Albert, Queen Paola, Prince Philippe and Mathilde already mingled with revellers early on Sunday, shaking hands and accepting gifts after a church service in the capital’s Cathedral of St Michael and St Gudula.

“Thank you sire,” read one sign held up high, as some people called out “Long live the king.” Giant Belgian flags and balloons in the national colours flew over the crowd.

Other European royals have not been invited to the festivities, as is tradition in Belgium.

Ahead of the abdication, much of the speculation had swirled around what dress Mathilde would wear. The new queen donned a cream-coloured, knee-length dress from Belgian designer Natan, paired with a light pink hat.

King Philippe, who is a qualified fighter pilot, wore the uniform of a lieutenant general, complete with a sabre. Later in the day, he was expected to change into the uniform of a general.

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