Harwich got off to a good start when in the 14th minute they piled on the pressure following a corner kick for Owen Rayment to net with a well placed shot through a crowded goalmouth
The Shrimpers continued to have the edge and just before half time Archie Corner hammered home their second goal.
Five minutes after the break Halstead were back in contention with a goal from the penalty spot
It was important for Harwich not to be phased by this set back and within another 5 minutes they mounted another dangerous attack for Connor Humphrys to restore their two goals lead with a clinical shot into the corner of the net.
Harwich manager Michael Clarke used his substitutes without there being any let up in the Shrimpers momentum and this was an excellent all round display from the whole squad.
With 10 minutes remaining the icing on the cake came when Owen Rayment tucked away his second goal with a shot from a tight angle.
Harwich team. Matthew Huggins, Luke Wallace, Max Carter, Owen Rayment, Louis Manhood, Tony Clarke Archie Corner, George Reid, Riley Ross, Ewan Livingston and Connor Humphrys. Substitutes: Samuel Gibbons, Samuel Howard, Drew Saunders, Theo Stevenson-Miller and Lewis Thompson.