Brighton Museum will hold a special drop-in exhibition to mark the 100th anniveasry of the Day Sussex Died.
Nearly 400 men from the Royal Sussex Regiment were killed in just a matter of hours at the Battle of Boar's Head on June 30, 1916.
Given the number of the dead from the county, the battle has become known as the Day Sussex Died.
The battle was fought by the county's pals battalions and as such nearly every town and village across the Sussex was affected.
The free drop-in day will be held at Brighton Museum on Thursday.
There will First World War re-enactors, items from the museum which can be handled and boards telling the stories of some of the casualties.
Members of the British Legion and relatives of the fallen will also be in attendance.
There are two sessions. The first is from 10am to 1pm and the second from 2pm to 4pm.
For more details visit brightonmuseums.org.uk/discover.
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