Mornin Tobin,
First of all, is hub on board with wanting another baby? I assume he is.
Being deployed for any amount of time is frustrating to both him and the fam, so he may be may be having a little battle fatigue. Give him some time and don't jump into bed announcing that you want to try for another baby. Now he feels like he has to perform. He could be as turned on as all get out, but has a hard time reaching orgasm, now he is trying to hard.
Help him relax and avoid the "let's have a baby" convo for a while. If he knows that this idea of a baby isn't always in the front of your love making, he may realize that he can make love to you without the baby thing pressing on his mind. Let him know that it will happen when nature is ready to let it. Don't forget, a married and deployed soldier doesn't get to have intercourse while away from their wives (at least they r not supposed to) so many times they have to take care of themselves by hand, (if u know what i mean) I don't mean to sound gross but they have to masterbate themselves to releive their tensions. This is normal.
Give him time to get back to normalcy, both physically and mentally. I'm sure you two will be fine and when the time is right, you will get pregnant. Just don't rush him right now.