Aquileia was founded in 181 BC as a Roman colony to prevent Celtic incursions in the Italian interior. Soon the Celtic tribes of N/Eastern Alpine Italy, Pannonia and other neighbouring regions, reacted by force to this colonisation and I suppose that the image depicts a modern reenactment of the battle
related to this reaction. I noted an interesting feature in the image, that is the elaborate but somewhat outdated linothorax of the fallen Italian warrior. It seems that he is a Venetian or Etruscan allied warrior of the Roman force (auxilia).
Creator and reenactment groups unknown but I suppose that they are local groups of Veneto and Friuli-Venezia. Kudos to them. The reenactment took place in 2013.