This is VERY common with kids your son's age! My son was exactly the same- either he constantly forgot to do things, or just took SO LONG to do them it was ridiculous!
At age 6, he is absorbing a LOT of new stuff, and honestly, our doctor told me, that my son's brain really was just not always able to focus on the task at hand. This is also worse with boys, btw than girls. You can punish for this- I admit, I raised my voice and took away cartoon privileges ,etc. but it never seemed to really help.
Here is what we did:
1) Write the chores down on a list. Set a kitchen timer and time how long it takes (on average) to do each chore. Show the kids that you will tell them the chore and then set the timer and - they're off! The kid who finishes first, doing the chore correctly gets a Popsicle or some other little treat. REWARD good behavior- just as important as negative consequences for bad behavior. It also gives your other kids a way to see that doing their chores is a good thing.
2)If your husband is deploying, maybe your son is feeling some pressure as the oldest kid. He probably has more responsibilities than the younger ones and is also maybe more aware from the tv, etc. that his dad is deploying and what that means. Talk to him about the responsibilities of showing a good example for the younger kids and that they look up to him to be the 'leader'.
Make sure he feels reassured about his dad's deployment- worry and trying to get attention because of it shows up in kids in a lot of different ways. Your son is still little- maybe even though he knows his dad has to go, this is one little way to try and get attention.
3)If you need to punish- take away things that your son likes that are NOT family activities like going to the pool. Does he play a video game or have a favorite cartoon, etc? If he does his chores, he earns 10 minutes of video game time per chore. If he does NOT do them, he needs to go to his room or finish the chore while his siblings get to watch a movie or play a game.
When my son got older, I would have him write lines. He hated it, but it did make him do his chores! Remember, the 'punishment' is usually BOREDOM. Playing video games or watching TV is NOT A RIGHT- just because the other kids do it,etc. He has to EARN those privileges through chores.
The one other thing we always stressed with my son was his attitude. We still do this today. It is not enough to DO the chore. You have to 'show willing' as we put it, and have a good attitude while doing it. A good example of this is feeding the dogs.
If my son says " I'll do it in a minute' or forgets, we sit down and have a talk about how much our pets love us and how they rely completely on us for food and water. I ask " How would you feel if you were really hungry and it was past dinnertime and you were waiting to eat and I said " just a minute until I finish this level on my game" and left you standing there hungry?" This makes him THINK about his behavior.
He earns an allowance of $10 every two weeks (on payday, he gets paid just like we do). However- he only gets this if he has been doing well in school, doing his homework with no nagging needed from me, and if he has a GOOD ATTITUDE about it and isn't sulking and grumping around. If I catch him sighing or acting like that, I remind him of the 'show willing' deal and that he will forfeit his allowance if he continues. Your son is a little young for this approach, but keep it in mind for later!
I also loved the other poster whose son didn't get the ice cream for dessert! My son has a sweet tooth and I don't allow dessert all the time, so not letting him have ice cream is a BIG punishment for him too, lol!
Good luck- I am sure you can handle this. It sounds pretty normal boy-stuff to me. Good luck to your husband and I hope he is safe during his deployment. God Bless!