VIRGINIA BEACH — After three days of digging, workers trying to solve the mystery of a sunken shipwreck at Lynnhaven Inlet on Friday finally found what they wanted most: the cannon. “We got it!” said Keith B. Lockwood, an environmental scientist with the Army Corps of Engineers. The corps is leading an effort to recover and identify pieces of the wreck, which is perhaps 300 years old, and clear the channel for boaters. Lockwood said a salvage crane was bringing up less and less debris when it hit something big and heavy. When the load was dumped onto the barge,...