No context, can’t help you. Large helicopters and East Texas is too vague. If it is a military exercise, there would be an announcement in the local press. Call the sheriff and ask what it was.
No announcement. No military base close. We do have the ports, I’m inland about 30 miles from the Port Arthur ports and saw the rail and port build ups during the Iraq invasion, but nothing since. It was very dark, but these were many large helicopters which I will assume were military.