Polish Catholics have been invited to join a rosary prayer on Saturday along the country’s 3,500-kilometre border to pray for their homeland and the whole world.

A group of lay people who organized the event, led by documentary film-maker and producer Maciej Bodasiński, say they chose 7 October because the day is celebrated in the Roman Catholic Church as the feast of Our Lady of the Rosary. The day is also the anniversary of the 1571 Battle of Lepanto, in which the fleet of the Holy League defeated the fleet of the Ottoman Empire.

A total of 319 churches close to Polish borders have been selected as gathering points for the event, but rosary services will be held churches across the country, as well as at other sites, including airports in ten Polish cities.

Polish bishops have asked all Catholics to join the action even if they are unable to travel to the border. “Families may pray in their homes, the sick in hospitals, and parish communities in their churches,” they said in a communique.

Organisers expect up to a million people to take part in the “Rosary on the Borders” event.