Minefields

[paul.mercer]

Gentlemen,
What was meant by a 'declared minefield' as it doesn't seem right to tell your enemies where you have laid them?

[Dave Saxton]

You don't want your own uninformed ships, and non navy traffic, and those of neutrals being sunk. Also some minefields are meant mainly to deny access of water to the enemy, so declaring an area mined also does that.