graph foo {
        graph [rankdir=TB];
        "General" -- "Colonel A"
        "General" -- "Colonel B"
        "Colonel B" -- "Captain A"
        "Colonel B" -- "Captain B"
        "Colonel B" -- "Captain C"
        "Captain A" -- "Sergeant A"
        "Captain A" -- "Sergeant B"
        "Sergeant B" -- "Private A"
        "Sergeant B" -- "Private B"
}