That time US troops called for air support from Grenada with a payphone
The list of Urgent Fury mistakes is a long one, but one snafu was so huge it became legend.
The basic story is that a unit on the island was pinned down by Communist forces. Interoperability and communications were so bad, they were unable to call for support from U.S. forces over the radio.
So a member of the unit pulled out his credit card and made a long-distance call by commercial phone lines to their home base, which patched it through to the Urgent Fury command, who then passed the order down to the requested support.