What the 45-year-old has gone on to do in West Yorkshire so far in his short spell has been phenomenal with every aspect of the club changed for the better under the 'Wagner Revolution'.
The Huddersfield Examiner will be celebrating the one year anniversary throughout this week with a number of articles and analysis, kicking off here with Part One of a month by month account of Wagner's year in charge.
After being officially unveiled at the club, David Wagner took charge of the last two games of the month - starting with tough trip to Hillsborough to face Sheffield Wednesday.
Town may have lost the game 3-1, Sean Scannell scoring the only goal for the side, but the fans could already see a change in style of play from previous manager in Chris Powell.
Wagner's next tricky fixture was his first home game in charge and a clash against high flying Middlesbrough, his side losing the game 2-0.
It would become a stop-start month in terms of results, but Huddersfield Town got off to the best of beginnings with an away win at Birmingham.
Town then lost 2-1 at home to Bristol City, Harry Bunn getting a late consolation goal before the first home points of the David Wagner era were sealed against Rotherham United at home - Ishmael Miller and Mustapha Carayol grabbing the goals in the Tuesday evening fixture.
Next up was a 4-2 away defeat to Brentford before Town bounced back by beat Preston North End 3-1 at home on Boxing day, Nahki Wells bagging a brace and Emyr Huws on the scoresheet too.
Town rounded off the month and 2015 with an away draw at QPR, Nahki Wells scoring an all important equaliser four minutes from time.
Huddersfield started the new year by beating Bolton Wanderers away on New Years day 2-0 - Joe Lolley and Mustapha Carayol scoring the goals in Lancashire.
Town then drew 2-2 at home to Reading in the FA Cup, Jamie Paterson and Wells on the scoresheet at the John Smiths Stadium before the side recorded their biggest win under Wagner against Charlton Athletic - 5-0 under the floodlights on a Tuesday night.
A 1-1 draw at Fulham was followed by the FA Cup replay against Reading, Town losing 5-2 on the night to set off a losing streak which would go on for the next three games - beginning with an away defeat against Brighton & Hove Albion (2-1) and Cardiff City at home (3-2).
As mentioned above, the poor run continued into the following month with a 2-1 away defeat to Preston.
Better things were just around the corner though, with Town winning the next two league fixtures - firstly against Nottingham Forest at the City Ground where a Matt Mills own goal and a super strike from Phillip Billing gave Town all three points.
The next win was at home to Wolves, Wells grabbing a 78th minute winner to mean Town had won two from three in February.
However, the month ended on a disappointing note for Town as they drew 1-1 away to MK Dons before then losing 1-0 at home to Ipswich Town.
Another up and down month in terms of results for Town, two wins and two losses making up the four fixtures.
First up was a 2-0 defeat at the iPro Stadium against Derby County, before Town picked up three points with a 3-1 home win over Reading courtesy of goals from Wells, Jamie Paterson and Flo Bojaj.
The win against Reading was proceeded by a 3-1 loss away to Burnley before arguably David Wagner's best result so far - a comprehensive 4-1 away victory over Yorkshire neighbours Leeds United at Elland Road.
It was arguably a case of 'after the Lord Mayor's Show' as David Wagner's side experienced two successive defeats at the start of the month, a 1-0 loss to Sheffield Wednesday at home and a 3-0 away defeat to Middlesbrough.
Town then went unbeaten in their next four, beginning with an entertaining 2-2 draw at home to Hull City which saw Harry Maguire score a 90th minute own goal before Adama Diomande equalised for the Tigers in stoppage time.
A 2-0 win against Blackburn Rovers at Ewood Park followed before Town drew their next two games by the scoreline of 1-1, away to Rotherham and at home to Birmingham City.
Their last game of the month was a long away trip to Bristol City, which saw David Wagner's side lose 4-0.
Town's last game of the season was at home to Brentford, and while a last gasp chance of a playoff place was out of the question for the visitors they were in impressive form.
If ever a match summed up the long hard overhaul that await David Wagner it was this game, Town succumbing to an embarrassing 5-1 defeat to sign off the season in disappointing fashion.
Find out how the 'Wagner Revolution' continued into the summer and the 2016/17 season tomorrow....