Thus Jonathan Forster accordingly conceived the idea of rising in a balloon, so as to pass over the besieging lines, and in that way reach the Secessionist camp.
The Governor authorized the attempt.

A balloon was manufactured and placed at the disposal of Forster, who was to be accompanied by five other persons.

They were furnished with arms in case they might have to defend themselves when they alighted, and provisions in the event of their aerial voyage being prolonged.
The departure of the balloon was fixed for the 18th of March.

It should be effected during the night, with a northwest wind of moderate force, and the aeronauts calculated that they would reach General Lee's camp in a few hours.
But this northwest wind was not a simple breeze.

From the 18th it was evident that it was changing to a hurricane.