Introducing a new dog

Question
I have a rescued 2 year old male boxer. He is amazingly sweet, and loyal to a fault. We are trying to introduce a new member to the family. She is an 8 month old "pocket" pittie. She is also very loving and sweet. When they were first introduced, it was going pretty well. Both were on leashes, inside the home and my male, Hans, commenced to sniffing things out. The new little girl tolerated this at first, but she was extremely scared. After a few minutes she snapped at him, and he turned aggressive. We took our time, crating him while she checked things out and warmed up. Once we let Hans out it was only a few minutes later that he turned and had her pinned and screaming on the floor. After that, she seemed to know that she needed to submit, and did. She'll lay in front of him and roll to her back with paws in the air. They seemed to be doing fine. But then when they both decided to play, it got bad again. I think my boxer is just too aggressive and she's confused on what is happening. He will stand in front of me if she tries to get near as if telling her "She's mine". My question (finally!) is, is this normal? Should I be worried or be trying something else? It has been 3 days. How long should I be prepared to handle this? And after how long is it time to consider her not joining the family?

Thanks in advance!

Answer
This is a bad situation.

You have a "rescue" Boxer: that means, you have no clue of his past, his abuse, his life. Second, he is two years old, set in his ways and should have been socialized with other dogs and cats in his younger years and apparently wasn't and now, it might be too late at this age..........

I don't know what a "pocket pittie" is, but it sounds tiny and this is bad. It's always a bad idea to put a tiny dog with a larger dog. Not good. One needs to go.

It is possible to train with supervision, but the problem is: when you aren't there, what happens?

Email me at jannieballiett@yahoo.com for more help in the meantime..........