YUKuN FIELD FUKCE.Uttawa, May IT —The government have decided to withdraw the Yukon field force. They will leave Dawson and Selkirk as soon as navigation opens. The peace and order of the district will, for the future, be attended to by the mounted police. It will be generally admitted that the military rendered good service, although a good mauy were opposed to their bein,* sent there in the first instance.