And while Portsnouth have been slow to get off the mark in January, a host of their rivals have wasted no time in adding to their ranks with some eye-catching deals.
Scroll down and click through the pages to see EVERY deal done in League One this month:
13. Milton Keynes Dons
In: Carlton Morris (Norwich City - loan), Louis Thompson (Norwich City - loan), Ben Gladwin (Blackburn Rovers) | Out: Brennan Dickenson (Exeter City) | Getty Images Photo: Pete Norton
14. Oxford United
In: Nathan Holland (West Ham - loan), Liam Kelly (Feyenoord - loan), Rob Atkinson (Eastleigh), Marcus Browne (Middlesbrough - loan), George Thorne (Derby County) | Out: Rob Hall (Forest Green - loan), Jordan Archer (Fulham) | Getty Images Photo: Nathan Stirk
15. Peterborough United
In: Reece Brown (Huddersfield Town - loan), Jack Taylor (Barnet), Sammie Szmodics (Bristol City - loan) | Out: Alex Woodyard (Tranmere Rovers - loan) | Getty Images Photo: Jordan Mansfield
16. Portsmouth
In: Steve Seddon (Birmingham City - loan), Reeco Hackett-Fairchild (Bromley), Cameron McGeehan (Barnsley - loan) | Out: Anton Walkes (Atlanta United), Luke McGee (Bradford City - loan) | Getty Images Photo: Dan Istitene