The Celts were a linguistic group which spanned across a wide geographic area and included numerous cultures and ethnicities. Because of this fact, the traditions, practices, and lifestyles of Celtic-speaking peoples varied considerably. The importance of warfare and the traditions surrounding war were one common thread of similarities throughout Celtic societies and cultures, from the earliest emergence of the Hallstatt culture (12th-6th century BCE) to the La Tene culture (5th-1st Century BCE).
This is a companion discussion topic for the original content at https://www.worldhistory.org/Celtic_Warfare/.