Peterborough United splashed the cash in the final hours of deadline day to secure the services of Hartlepool United defender Jack Baldwin.
The Posh spent £500,000 on the 20-year-old who signed a four-and-a-half-year contract at London Road having impressed for Pools in recent seasons.
Fellow promotion hopefuls Preston North End also acted on Friday to sign Bolton Wanderers striker Craig Davies on loan until the end of the season.
The 28-year-old instantly repayed Simon Grayson's faith by netting in their 2-0 win at home to Notts County on his debut.
There was some inter-League 1 movement as Nicky Adams left Crawley Town to sign a two-and-a-half-year deal at Rotherham United.
Leyton Orients were one of the busiest of the League 1 teams, signing Charlton Athletic goalkeeper Ben Alnwick and Burnley midfielder Marvin Bartley on permanent deals.
The O's also extended the loans of Jamar Loza and Jamie Ness.
Oldham Athletic saw movement in and out of the club on deadline day with James Tarkowski leaving for league leaders Brentford. However, the defender will return to Boundary Park when the loan window reopens.
Arriving at the Latics was striker Jon Stead - on loan for a month from Huddersfield Town - in addition to the signings of James Wilson, from Bristol City, and Stockport's Rhys Turner. Stead and Wilson both made their debuts as Oldham upset the odds to win 1-0 at Swindon Town on Saturday.
Sheffield United acted late in completing the permanent signing of full-back Bob Harris after his loan spell at Bramall Lane from Blackpool. Harris' arrival added to the good work done by Nigel Clough in bringing in Livingston midfielder Stegan Scougall and Cardiff defender John Brayford earlier in the transfer window.
One of the biggest transfers within League 1 also happened earlier in the final week of the transfer window when Leon Clarke completed a much-publicised move from Coventry City to Wolverhampton Wanderers.
His move across the West Midlands was eventually confirmed on Thursday in a deal close to £750,000. That acquisition came in anticipation of Leigh Griffiths' move up north to Scottish champions Celtic, which was confirmed on deadline day.
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