All the boats of the U-66 class saw active service, and all but one boat, U-68, had wartime successes; U-69 and U-70 both sank over 100,000 tons of Allied shipping.[1] U-68 was sunk by the British Q-ship HMS Farnborough in March 1916, and was the first boat of the class to be lost during the war.[1] U-69 and U-66 were lost in July and September 1917, respectively.[7] U-67 and U-70 both survived the war and were surrendered to the United Kingdom in November 1918,[6] and both were broken up by 1921.[1]