French leave

French leave (sometimes a French exit, an Irish goodbye or an Irish exit, or in French a filer à l'anglaise) is a departure from a location or event without informing others or without seeking approval. Examples include relatively innocuous acts such as leaving a party without bidding farewell in order to avoid disturbing or upsetting the host, or more problematic acts such as a soldier leaving his post without authorization.

The first attestation of the phrase in the Oxford English Dictionary is from 1751, a time when the English and French cultures were heavily interlinked.