The Northern Ireland Secretary is to represent the UK Government at the annual Somme commemoration in France.
She will be taking part in a Royal British Legion service of commemoration at Thiepval, a memorial to the missing at a village on the frontline which was flattened during the bombardment, and Somme Association services at the Ulster Tower and Guillemont. She will lay wreaths on behalf of the Government.
Ms Villiers said: "It is a great honour for me to be at Thiepval to represent Her Majesty's Government on this deeply-moving and solemn occasion. We must never forget those who gave their lives for our country during that terrible conflict. The losses at the Somme were without parallel in British military history."
The 36th Ulster Division suffered massive casualties but one eye witness said their attack was one of the finest displays of human courage in the world and Ms Villiers said the Somme had left an indelible mark on Northern Ireland.
"I say this mindful of the vital role that so many men and women from Northern Ireland continue to play in our superb armed forces across the word today," she added. "It is also fitting that today we remember the sacrifice of the 16th (Irish) Division at Guillemont and elsewhere. They too suffered terribly."
The Battle of the Somme, whose 97th anniversary is commemorated this year, began on July 1, 1916 in the high expectation of a major victory that would bring the carnage of the First World War to an end. By the time it petered out the following November, more than one million soldiers from both sides had died.
Among the victims were thousands of Irish soldiers, with many more wounded. The catastrophic loss of life was exacerbated by much of its occurrence on the first day of the Battle and two days in the following September.
About 5,500 casualties were from the 36th Ulster Division on July 1. The 16th Irish Division had 4,330 casualties in September, of whom 1,200 were killed. These came mainly from the other three provinces.
Added to these were the Irish soldiers who fought in other divisions as part of the regular army or in the newly raised battalions. The total number of Irish casualties cannot be calculated with certainty.