Army officials went with Mac OS because it has no command shell and doesn't support remote log-ins.

CNN: Army Web site ditches NT for security reasons

Of course the Mac was created in part as sort of a backlash against the command line interface of DOS (typing long strings of complicated computing commands, not pointing and clicking with a mouse like we're used to now), though Mac OS X now boasts a Unix Shell terminal with its own command line interface.

FORBES: Dual-Personality Macs