Hadleigh United started well and were rewarded when they took the lead.
The match became end to end and Harwich equalised when Dylan Crowley broke through and rounded the goalkeeper before keeping his cool to finish from an angle.
The Shrimpers had come back well and gained the lead in the second half through Luca Rhodes, who scored an opportunist goal, pouncing when the visitors' defence was uncertain, to net with a well-placed shot.
Harwich were buzzing now and with the wind at their backs, a well-struck corner was headed home by danger man Crowley (pictured with manager Luke Harrison).
Playing excellent, attacking football, Harwich's 4th goal came when Jack Elvestad made a run and, from more than 20 yards out, rifled his shot into the net.
Hadleigh had played their part in an entertaining match and twice forced Harwich keeper Oscar Finbow to pull off excellent diving saves.
Harwich have a mouthwatering fixture next Thursday when they entertain near neighbours Little Oakley, who are currently top of the league with a 100% record from their 4 matches. There looks sure to be a good crowd and an exciting atmosphere on the Royal Oak that night.