James Hemming pleaded guilty to wounding with intent after a 17-year-old girl was badly injured in Fratton.
Search For Havant Teenager's Attacker
Police are appealing for anyone with information as they continue to investigate an assault on a teenager in Havant.
The assault happened sometime between 10.00am and 2.00pm on August 8, 2013, in St Albans Park when a 13-year-old girl was involved in an altercation with a group of young teenagers.
As she and her friend walked away from the group, a discarded chair back (which had been lying on the floor) was thrown at the victim.
The girl suffered injuries to her neck and head and had to be seen in hospital the night after the attack where she was treated for concussion and whiplash along with headaches and dizzy spells.
Investigating officer, PC Angela Morrell of Havant DCID said:
"This was a nasty assault which has left the victim still suffering from dizzy spell two months on.
"We are appealing to anyone who was in the park at the time of the attack to contact us if they remember seeing this incident or have any information that will help us to identify the person responsible."
Anyone with information can contact PC Morrell at Havant DCID by phoning 101. Information can be given anonymously by phoning the independent Crimestoppers charity on 0800 555 111.
Dorset and Hampshire officers will be carrying out extra patrols until New Year's Day.
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