The former First Lady made a weary but heartfelt attack on her husband's successor in the White House.
It lit up social media and won wild praise among anti-Trump activists.
At times she appeared close to tears and she won rave reviews - and made many Democrats secretly wish Michelle was on the ballot, not Biden.
Trump angrily fired back, calling her a divisive figure and observed that her convention speech had been prerecorded and didn’t deserve the "fawning praise".
This Democratic Party national convention is unlike anything in the history of presidential politics.
Gone is the great theatre of an American convention hall packed with delegates, passion, activism, balloons and ticker tape.
Instead, in its place is an entirely virtual, online prime-time political gathering - a vast combination of video feeds, political messaging, patriotic symbolism and an appeal for voters to save America.
Overall, Democrats will be satisfied with the convention so far.
It isn’t flawless.
Many Americans won’t engage with a nightly two hour political extravaganza.
In many bars in Milwaukee people are watching sports channels, not the news networks.
But the convention reveals the urgency that Democrats believe this moment merits.
As Joe Biden often says, America's character is on the ballot.
This was the basic pitch: that Democrats can rescue a failing democracy, and a flailing economy; that they will bring science not hoaxes and conspiracy theories to the White House.
But the party will only know in 76 days whether this convention really succeeded in its one and only objective - putting Joe Biden on a glide-path to the White House.