A late tackle by Gillingham's Mark Bentley on Zigor Aranalde saw the winger ordered off after 73 minutes after receiving his second yellow card with the score still at 1-0. And the one-man advantage for Carlisle soon paid dividends as they ran the hapless Gills ragged.
Captain Peter Murphy opened the scoring for Carlisle with a clever free kick that flew under the jumping wall leaving keeper Romain Larrieu stranded. Bentley then had a low drive beaten away by Carlisle's Keiren Westwood before Murphy almost made it 2-0.
The second half opened with Bentley getting his first booking for a foul on Westwood and Gillingham striker Gary Mulligan was unlucky to see his header hit the top of the bar. Five minutes later Jeff Smith almost put through his own net but once again the woodwork intervened to save the Cumbrians.
After Bentley's sending off Carlisle found their rhythm and Jeff Smith's inch-perfect cross was nodded in by Luke Joyce for his first senior goal after 81 minutes. Two minutes later Kevin Gall made it three when Danny Jackman's attempted clearance bounced off him and into the net.
With two minutes left, substitute Johann Smith was hauled down in the area and Danny Graham slotted home a penalty. The rout was completed in injury time when Gall crossed for the unmarked Graham to head in his second leaving the disappointed 323 travelling fans with a long journey home.