The weather was perfect for football, with the slight feeling of cold offset by the late winter sunshine, and it was United who kicked towards the Warwick Road End from the off.
Swindon, adorned in yellow shirts, mounted the first attack down the left flank and a blocked cross brought a corner that was cleared by Guy.
Feeney stepped across to stop a Tomlinson run down the same channel, after he had skipped through three challenges, with the away team looking to be in a confident mood.
The Blues were on the attack on seven minutes when good footwork from Riley saw him rob possession deep inside his own half. A raking crossfield pass was touched on by Patrick, and he jinked past Hunt to deliver low. That was sent out of the box, but Guy wasn't too far away as he drilled a 20-yard left-footed stinger just over the bar.
Swindon found an overlap through Hunt as they sent men forward, and he made his way out of a tight spot to send it into the area. Barry fizzed a first-time effort into Davison's back and had his second volley was diverted over the target.
It was the home side's turn to attack in what was a lively start with another accurate pass forward from Feeney, which Patrick took in his stride. He fed it back to Guy, but Mellish couldn't get out of the way when a goalbound rocket came his way. Guy recovered it, and Riley immediately showed. He made space to shoot but it was straight at Wollacott.
The visitors took the lead just past the quarter hour when a quick exchange of passes put McKirdy clean through. He found power with his cloase-range finish that left Howard with no chance.
United aimed to respond quickly and Patrick was again the outlet as he drifted into space. He dropped a shoulder and popped it across the face of goal but it was just too far in front of Mellish.
A Guy free kick from deep was initially hooked clear but Roberts had stayed outside the area, and he was able to guide it towards the back stick. Whelan helped it on, but it was a difficult chance and Mellish volleyed it past the upright.
Windsor tried his luck from distance as the hosts waited for a spark, but Wollacott was well-placed once again to deal with it.
Simeu and Davison were involved in a tangle when the pair tumbled 10 minutes before half-time, and the pair received a booking for their troubles.
A long throw from Roberts was guided on by Mellish with Carlisle desperate to create chances, and Windsor shielded it with his back to goal. He stayed tight to his man, touched it, and shot, but it was blocked at source.
Mark Howard was needed just before the break when Aguiar sliced the defence in two with an accurate through ball. Barry cut inside to shoot but the keeper dived high to parry.
Feeney popped a header from a Guy free kick into the stands in time added on, but there was much to talk about as the teams headed up the tunnel.
Jordan Gibson replaced Owen Windsor at the start of the second period, and he was immediately involved when he was chopped to the floor having ridden out a tackle in midfield. He then won a corner as he delivered from the quickly taken set-piece.
A deflected shot from Tomlinson sat up nicely for Howard to catch after a McKirdy run had been curtailed at the other end, and the stopper had to sprint off his line to smother from Barry as he latched onto a flick from Davison.
Another home corner was won when Riley pushed through from the middle of the park with the ball at his feet, and Gibson centred, only to see it clip a thigh.
But it was the away team who doubled their advantage when McKirdy turned provider as he was released into space. Davison timed his run to beat the offside flag, and he picked his spot in the bottom corner with an emphatic finish.
It became three just two minutes later when McKirdy was once again left to run free down the right wing. His delivery was dummied by Davison, and the unmarked Louie Barry was able to sweep it into the empty net.
Joe Riley had an attempt charged down as he tried to lift the mood, and Tomlinson went close for the yellow shirts when he rattled one just past the post from the edge of the area.
The game was halted by a pitch invader just after the 70-minute mark, and it was United who got forward first after the restart with a ball over the top for Dennis, who took it down well. He struck it early but Wollacott gobbled it up.
A second pitch invader caused more disruption, but Swindon were comfortable with seeing the game out as they sat deep to stifle the closing stages. And they almost grabbed a fourth late in the day when Parsons fired a low shot through legs and an inch wide.