Insiders said crews were forced to carry out “six weeks' work in six days” to get the ship ready to sail.
Former First Sea Lord Admiral Lord West said: “There is no understanding in government of the importance of maritime power.
“There isn’t a single warship between Singapore and Gibraltar. It’s astonishing that no one had the geopolitical sense to make these decisions earlier.”
A Ministry of Defence spokesman said HMS Dragon was currently heading to the eastern Mediterranean to help “safeguard UK assets and interests”.
He added: “It’s not uncommon for ships to continue final maintenance and preparations while on deployment at sea, shortly after sailing.”