Women are to be allowed to serve on Royal Navy submarines for the first time, Defence Secretary Philip Hammond has announced.
The first female officers will begin serving on Vanguard class nuclear-powered submarines from late 2013, Mr Hammond said.
They will be followed by women ratings in 2015. Women will also be able to serve on the new Astute class submarines from about 2015.
"Operational effectiveness has to remain the watchword for everything we do and we will continue to learn from our experience," Mr Hammond said in a keynote speech to the Royal United Services Institute in London.
"We will change and adapt with the evidence and the circumstances. We will value our history and tradition - but we will not be slaves to them. In that spirit, I can announce today that I have accepted the recommendation of the First Sea Lord that women should be allowed to serve in submarines in the future."
The decision to lift the ban on women submariners follows an 18-month review by the Royal Navy looking at the legal, operational, health, social, technical and financial issues.
Women have previously been excluded from serving on submarines due to concerns that higher levels of carbon dioxide in the on-board atmosphere pose particular risks to female health.
Recent research by the Institute of Naval Medicine concluded that these risks were unfounded and there were no medical reasons for maintaining the ban.
The Second Sea Lord, Vice Admiral Charles Montgomery, said: "This carefully considered decision will allow the Submarine Service to draw on the widest range of talent and skills of our people - those in service and those yet to join.
"It will give our women the same opportunities as men to enjoy a fulfilling and rewarding career in the Submarine Service."