Keep your powder dry
Meaning
Stay prepared and avoid acting rashly.
Usage
Used when caution and readiness go hand in hand.
Origin & History
Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.
Gunpowder had to remain dry to fire properly, so the phrase means stay ready.
Dating to the 17th century, it became a military proverb.