Post apocalyptic: I think a comet or something hit earth which cause storms that wiped out lots of people. The area the main characters are in was saved because it was practically in the mountains.
Loosely military themed: The main character has had training and throughout the story he trains his new found town. The big adversaries in the story are also well trained.
Group effort: Most people try to work together for the greater good of the town. There are a couple bad apples who just want things their way even as far as disagreeing with the main characters good ideas for safety and progression.
Little things I remember: The main character saves two kids(teens) from a gang like group. He convinces the town to accept him by sneaking in their weak defenses. It's definitely a decent length story over 10 chapters.
As always thanks for any help at all in finding this story.