The Shaymen produced a stirring display to see off their League Two opponents and set-up a mouth-watering second round tie.
If they play like this at lunchtime on December 1, they’ll have a real chance of another upset.
Man of the match contenders peppered the Town line-up; Dayle Southwell was industrious and clever up-front, Matty Brown was his usual towering presence at the back, and Niall Maher was an effective presence in midfield, anticipating well and working hard.
But that work rate was in abundance from every Town player on the night, and they thoroughly deserve their day in the national spotlight.
As expected, Ryan Sellers replaced the suspended Joe Skarz, while Jordan Preston also came in for Sanmi Odelusi.
Jamie Fullarton even had the luxury of naming six substitutes.
With a pot of £111,000 for the winners, plus a televised home clash, the game was the most important of Town’s season so far, and they played like it.
Town were hungrier, quicker and more aggressive than Morecambe, and set the tone for a terrific first-half with Sellers’ long-range shot, which was spilled by Morecambe keeper Mark Halstead, but Josh Staunton was unable to react quickly enough to turn in the rebound, and it spurted agonisingly wide.
But the fact Sellers had attempted a shot from around 40 yards summed up The Shaymen’s adventurous approach, flying into tackles, pressing high up the pitch and attacking the hosts with zeal.
The goal emphasised the purposeful thrust of their attacking play, as Southwell showed excellent control and awareness to hold the ball up before finding King, who shimmied in the face of a Morecambe defender to earn some space and fire low across Halstead from an angle.
Staunton was probably the most relieved man in The Shay.
Sellers’ corner then appeared to bounce off the bar with the aid of Halstead’s palm, with Morecambe caught in the headlights of Town’s start.
A superb block by the typically-energetic Jacob Hanson took the sting out of A-Jay Leitch-Smith’s shot from 12 yards out, but the visitors were struggling to respond.
Matty Kosylo then had a goal contentiously ruled out for offside when Southwell’s lofted free-kick was nodded into his path, with the assistant leaving the decision suspiciously late to curb Town’s celebrations.
A second goal wouldn’t have been undeserved, but was also what Town needed to put clear daylight between them and their opponents.
The Shaymen were sharp and fluid in attack, as evidenced when Southwell and Kosylo swept the ball from one end of the pitch to the other from a Morecambe corner to earn Town a corner.
Josh Staunton fired over near the angle of the six-yard box after the excellent Maher saw his shot turned behind having played a delightful pass to Kosylo and got the ball back.
Morecambe could only muster half-chances and long-range hit-and-hopes, while Town were brimming with endeavour, as if the low points of their recent winless run had happened to a different team.
By half-time, the main worry was that they hadn’t turned their performance into more than a single goal lead.
Rhys Oates sent a warning shot crashing narrowly over moments after the restart, but Matty Brown went close to that crucial second goal with a diving header with of the near post from a corner.
An hour in, and Morecambe weren’t offering anything that the Town defence couldn’t deal with, although Halifax had come off the pace a little and were inclined to protect their lead as much as add to it.
Nathan Clarke produced a magnificent block to repel a goalbound Morecambe shot as the visitors gradually increased the pressure; that second goal would have been nice at times like this.
Oates again went close with a rising drive across goal on 80 minutes as Town dug deep to preserve their slender advantage, but did so with a voracious work ethic.
AFC Wimbledon won’t relish a trip to The Shay on this evidence.
Halifax: Johnson, Hanson, Brown, Clarke, Sellers, Staunton, Maher, Preston (Odelusi 90), King, Kosylo, Southwell (Edwards 87). Subs not used: Rowley, Duckworth, Lenighan, McLeod.
Scorer: King (13)
Shots on target: 4
Shots off target: 6
Morecambe: Halstead, Mills, Conlan, Old, Cranston (Tutte 56), Wildig (Oswell 77), Lavelle, Mandeville, Oates (Ellison 87), Oliver, Leitch-Smith. Subs not used: Szczepaniak, Kenyon, Thompson, Yarney.
Shots on target: 2
Shots off target: 11
Referee: Martin Coy
Town man of the match: Dayle Southwell