While it's a good idea to bring cash and checks with you on your deployment, you may also want to secure a check card from your bank or credit union. Check cards are convenient and easy to carry around. Many check cards are affiliated with global credit card companies like Visa. Any vendor who accepts credit card payments from these companies should also accept a check card as payment.
You may not need to ask your bank for a check card. Several financial institutions combine check cards with ATM cards. Just bring your ATM card along on deployment.
There's a major difference between a credit card and a check card. Credit cards extend credit to you and you repay the credit card company with interest for any purchases you make with the card. Check cards debit any charges from your checking account. When you use a check card, you won't have to worry about paying interest on the purchase later.