It’s believed that screens containing photos of individuals who died on the first day of the battle were ‘destroyed’ between Friday June 17 and the following day.
Officers are appealing for residents with any information to come forward.
Sergeant Alun Oliver, from the Barnsley Central Neighbourhood Policing Team, said: ““This looks to be wanton damage to a much-loved memorial which has caused anger among those who have seen the results.
“It is unclear the exact time the damage was caused, so we are appealing for anyone who may have been in the vicinity on the evening of June 17 and may have seen or heard anything suspicious, or anyone who has any CCTV or dash-cam footage which may have captured something, to come forward and help us with the investigation.”
Anyone with information which could assist with our enquiries is asked to call 101, quoting incident number 333 of June 22.