Brig dominated the first period but failed to make the most of their chances and the sending off of Paul Dawson in the second half changed the complexion of the game.
Down to 10 men, Milligan’s men lost their way and conceded twice shortly after the hour mark.
It had all look so promising as the visitors dominated proceedings in the first period.
The best fans photos from Preston North End's 4-1 win over Huddersfield Town in the Carabao Cup.
Preston North End provides injury update on Manchester United loanee and addresses specualtion linking them to another Red Devils youngster
Manchester United youngster being tested by Preston North End on a 'daily basis' after sparkling debut
Wigan remain Championship relegation candidates but bookies' odds drift for Preston North End and Blackpool
Player Ratings: Huddersfield Town 1-4 Preston North End - Carabao Cup win on the road
Trinity keeper produced a great double save to thwart Joe Rodwell-Grant and Dawson. Matt Thomson and Dawson went close soon after but Brig could not break the deadlock.
Dawson then saw red and Brig fell behind courtesy of Ciaron Keane and Bradley Grayson.
Meanwhile, Lancaster City suffered FA Trophy agony as they were beaten on penalties by Morpeth Town after a thrilling encounter at Craic Park.
The Dolly Blues forced the match into a penalty shoot-out with a last-ditch equaliser from Liam Brockbank after a see-saw battle. Unfortunately, Andy Teague missed from the spot as City lost out 5-3 in a penalty shootout.
It was the Dolly Blues who drew first blood early when Rob Wilson fired home from 12 yards after Christian Sloan was brought down.
Michael Turner equalised on the half hour mark only for City to edge ahead again shortly before half-time after Rhys Turner sprinted clear and slotted home.
Despite being reduced to 10 men, Morpeth equalised and then went ahead through Ben Reid and Liam Henderson respectively.
Brockbank pulled the scores level in the 89th minute when he fired a brilliant free-kick home but unfortunately it was Town who prevailed in the shootout.
Elsewhere, Clitheroe drew 2-2 at 1874 Northwich in the NPL West Division. Kendal lost 2-0 at Glossop.
In the FA Trophy, AFC Fylde lost 1-0 at Solihull Moors but Southport beat Farsley 3-0.
Support us and become a subscriber today. Enjoy unlimited access to local news, the latest football stories and new puzzles every day. With a digital subscription, you can see fewer ads, enjoy faster load times, and get access to exclusive newsletters and content. Click here to subscribe.