We know your agents already.

If you will secretly inform them that those who speak in my name," and he took his card from the table, and gave it into Medina's hands, "are men to be trusted, it will be enough." Jose Medina agreed.
"I will give them instructions." "And yet another instruction if you will be so kind, to all your captains." "Yes ?" "That they shall report at the earliest possible moment to your nearest agent ashore, the position of any submarine they have seen." Jose Medina assented once more.
"But it will take a little time, senor, for me to pass that instruction round.

It shall go from captain to captain, but it will not be prudent to give it out more widely.

A week or two--no more--and every captain in my fleet shall be informed.

That is all ?" Hillyard was already rising from his chair.