DS is in year 1; he’s one of the oldest in his class (October born).
DS has a friend who I will call Martin .
Martin is a bit of a pain - constantly in trouble at school for various things.
My DS is also being a bit of a pain at school - being silly , talking when he shouldn’t etc.
I’ve discussed DS behaviour and told him that he and Martin need to be separated if they can’t control themselves.
My DS has more than once been confused with Martin and told off for something he didn’t do (I know this as DS wasn’t in school at the time of an incident but it was assumed he was involved as he is always with Martin).
Martin likes to rough house with anyone and everyone - whether they want to or not.
He likes to wind up other children .
On Monday last week, Martin started rough housing with my DS and my DS joined in . Other children also joined in and it went a bit far with the children kicking and hitting each other in “play” 
This happens often and DS is often telling me stories about who has hurt who.
I’ve repeatedly told my DS to not join in.
I found out last night that on Friday last week , the rough housing started again with lots of children involved but they were told off for it and it stopped.
Martin and his friend then started again by pulling my DS (who was playing by himself) to the ground and my DS then kicked Martin along with some other children (also kicking Martin) .
When I asked my DS about this , he lied to me and made up a story about how Martin fell over and DS landed on him
DS is going through a phase of lying at the moment and I lost my temper with him.
The truth did out and I sanctioned him yesterday for lying and for kicking another child . He lost his screen time etc .
DH has returned from working away and said I was too harsh - it was only rough play .
WIBU in sanctioning DS?
I’m doubting myself now, but the thought of my DS kicking another child deliberately (whether in play or not) infuriates me .