Whether as a direct result of the Battle of Portland or the accumulation of experience gained over some years, in March 1653, Robert Blake wrote the Sailing and Fighting Instructions, a major overhaul of English naval tactics, containing the first formal description of the line of battle. The success of this new formation was evident in the Battle of the Gabbard in June 1653, when the English fleet not only defeated the Dutch in a long-range artillery duel but suffered so little damage that it could maintain a blockade rather than sending many ships to port for repairs. The Dutch, in contrast, relied less on linear tactics, preferring to close with English ships to board and capture then as late as the Battle of Lowestoft in 1665, and they also retained numbers of slow and badly armed hired merchant ships in their fleet as late as that battle, when the English fleet was already questioning their use.