The parade on the Avenida da Liberdade, which is being organised by the country’s League of Combatants and the General Staff of the Armed Forces (EMGFA), headed by Admiral António Silva Ribeiro, is to entail special security measures and traffic restrictions in the capital from 10pm on Friday, at the top of Parque Eduardo VII.

At a news conference on Friday, the spokesman for EMGFA, Commander Coelho Dias, said he believed that the ceremony, in which more than 4,500 members of the military and police are to march, is the largest "for a hundred years". He stressed that its purpose was "to honour peace [and] the memory" of the some 100,000 Portuguese who fought in the Great War of 1914 to 1918, and in particular the 7,500 who died in the conflict.

The event, he added, will pay "due homage and stimulate national pride" as "an act of citizenship."

The organising committee is chaired by Portugal’s president and supreme commander of the armed forces, Marcelo Rebelo de Sousa, who is to address participants at 11.30am.

Alexandre Coimbra, a spokesman for Lisbon’s PSP police force, said that Saturday would see traffic restrictions imposed downtown from 2pm, and Sunday from 8am. He called on anyone who wants to watch the parade to use public transport, especially the metro – while stressing that the Avenida station will be closed.

As a security precaution, Avenida da Liberdade will have areas cordoned off for public, with railings and anti-vehicle obstacles. In addition, he said, "a few thousand police" from several units are to be deployed in the face of the "significant risk" that the force associates with initiatives on this scale and the presence of top officials.

The ceremony is to involve 3,437 members of the armed forces, 390 members of the National Republican Guard (GNR), 390 PSP officers, 160 former combatants, 80 members of foreign armed forces – from Germany, the US, France and the UK – and 180 students from a military college and a military school.

In addition, almost 200 vehicles and 86 horses are to take part. There is also to be a naval component to the event, with a frigate and an ocean patrol ship anchored in the River Tagus, while there is to be a flyover by air force F-16 jets as a tribute to the dead.

Portugal participated in World War I on the side of the Allies, in all sending around 100,000 men to the Western Front as the Portuguese Expeditionary Corps, in 1917.

Portuguese forces were also engaged on the front in Angola in 1914 and 1915, in Mozambique between 1914 and 1918.