To understand what makes a coup succeed, as recently happened in Sudan and Algeria, or fail, as it did this week in Venezuela, it helps to consider the strange events in Libya a half-century ago.

For much of 1969, the country was filled with rumors of an imminent coup. In September, a handful of military vehicles rolled up to government offices and communication centers, and a terse statement announced the end of Libya’s decrepit monarchy.

Army units around the country, assuming that military chiefs were leading the coup and expecting them to show up at any moment, bloodlessly secured the rest of Libya. Foreign powers quickly recognized the new government. Nobody bothered to check who was leading the takeover.

A week later, an unknown 27-year-old army signal corps lieutenant announced that he and a few dozen low-level officers had in fact staged the coup. His name was Muammar el-Qaddafi.