Schoolchildren and officials from Pas-de-Calais joined the mayor of Richebourg, Gerard Delahaye, in Worthing on Saturday for a day of celebrations.
Ellen Chapman, who was mayor of Worthing from 1920 to 1922, first formed the connection with Richebourg after the World War One battle known as The Day Sussex Died.
The Battle of the Boar’s Head took place near the northern French settlement in 1916 and in less than five hours, hundreds of men from the Royal Sussex Regiment were killed, including 22 from Worthing. A further thousand men were wounded in the battle.
Mr Delahaye was the first mayor of Richebourg to visit Worthing since mayor Paul Boulainguez came in 1921. He was awarded the Freedom of Worthing by mayor Alex Harman in a ceremony at Worthing Town Hall.
Mr Harman said: "The whole event went really well. It really was civic pride at its best. The support from both sides of The Channel was fantastic.
"I was so pleased to see schoolchildren from both towns take part in the event, too, as it shows that the young people of our towns are committed to seeing the link grow and continue in future years.”
Chatsmore Catholic High School has been developing a link with the Marcel Lejosne School in Richebourg and students visited the town last summer as part of a battlefield tour.
This year, the students collaborated on an artistic project to celebrate the link between the two towns and a fabulous piece of stained glass, designed with the help of artist Naomi Frances, was unveiled on Worthing Pier on Saturday, with a duplicate piece created for the community of Richebourg.
Julian Morgan, assistant head teacher at Chatsmore, said: "It's not only a chance for our pupils to appreciate how close to home events of the First World War were felt but also to engage with children from Richebourg in a cultural exchange while exploring our shared history.”
The glass unveiling followed a short commemoration service at the Battle of Boar’s Head memorial in Beach House Park.
Mr Harman said: "Honouring the town of Richebourg by bestowing the the freedom of the borough of Worthing upon the mayor’s office is long overdue. It's important to not only remember the past but also look to the future."