 Instead, the fleet was positioned in front of the Medway, near Chatham Dockyard, although it risked being confined to the Thames estuary by the same easterly winds that would allow the Dutch to cross.Since James believed the Dutch would seek to destroy the English fleet prior to an invasion, it would be advantageous to refuse battle, a strategic concept known as the fleet in being.This was indeed the original Dutch plan – though they too, to lower the cost of the invasion, had not activated any heavier ships – but as they moved into autumn, conditions deteriorated rapidly for those on the transports; they therefore decided to sail in convoy and avoid battle.