Okay, so, my dad got deployed to Guam and left Tuesday night. My brother (age 7) , quite possibly taking it harder than anyone else in the house, has really been really acting up and being mean to the kids at his school since he found out a few months ago that my dad was leaving.
Just yesterday, my poor mother had to go pick him up because he threw a cinderblock at one kid, punched another, and was disrespectful tward the teacher.
It's odviously related to my dads deployment and I was wondering if anyone had any ideas on how I can get him to behave and accept that my dad won't be gone forever. We've tried to punish him, but he just retaliates more when we do that.

I need help, it upsets my already sick mother and I want to do something to get him in line. Any tips?

Tell him he needs to be the man of the house.

Oh dear...sound's like a job for super-nanny ;)
I hope thing's start to get better.

Is there a counselor at school who can talk with all of you? Sounds like he needs to vent his anger and sadness abt your dad being gone. He probably has heard or seen stories of military personnel leaving for duty and not returning home. He is probably scared too. Anger forms as a result of many feelings, sadness, depression, frustration, etc. He is speaking out in a way that is harmful to himself and obviously to others.

sounds like he's expressing his unhappiness through the defiant behavior. i would suggest having him talk about his feelings with you or someone else he's close to. just ask him if he misses your dad and how it makes him feel. he's clearly upset about it, but giving him the chance to talk about it more in depth could help him release those emotions and no longer feel the need to deal with them in unhealthy ways.

sounds like he's expressing his unhappiness through the defiant behavior. i would suggest having him talk about his feelings with you or someone else he's close to. just ask him if he misses your dad and how it makes him feel. he's clearly upset about it, but giving him the chance to talk about it more in depth could help him release those emotions and no longer feel the need to deal with them in unhealthy ways.
Right, I plan on doing that. Thanks.

It might be helpful if you took him to see a therapist. At that age he might not even understand why he is so mad. Since your dad in the military I would think you could get a therapist through whatever branch your dad belongs too.