It also made for some uneasy bedfellows, with one Labour candidate, Toby Perkins, using a widely tweeted picture and quote from Margaret Thatcher to register his opposition to personal attacks.
Mr Miliband said the defence secretary had demeaned himself and his office. But Prime Minister David Cameron said Mr Fallon was "absolutely right".
A glance through the social media accounts of established political party names and official accounts also reveals a good deal of negative campaigning.
Boris Johnson, Mayor of London and Conservative candidate for Uxbridge and South Ruislip, has been leading some of the Conservative attacks via social media, with tweets such as this one:
John Prescott, Labour's former deputy prime minister and prolific tweeter, has also been targeting candidates from his party's opponents.
The Liberal Democrats have also been tweeting their own targeted videos.
With weeks to go in one of the tightest polls in living memory, there may yet be further negative campaigning, but whether it gets quite as personal as previous campaigns - such as these examples below - remains to be seen.
In 2001, Labour was seeking a second term under Tony Blair. It targeted the Conservative leader William Hague by planting Baroness Thatcher's hairstyle on his head, in one of the most notorious campaign posters in living memory. Labour went on to win re-election by a landslide.
Creative photoshopping had already been used by its opponents in 1996, when the Conservatives unveiled this "demon eyes" poster of Tony Blair a year ahead of the 1997 election, which saw Labour sweep to power.
Compiled by Stephen Fottrell.
Thursday was seen as the day the 2015 UK general election campaign turned negative, with many reacting on social media to Defence Secretary Michael Fallon's attack on Labour leader Ed Miliband.