What event sparked the animals' rebellion in Animal Farm?

Old Major's speech put the idea of rebellion in the
animals' minds, but they didn't have any idea when it would begin or whether "it would
be within their own lifetime." Snowball and Napoleon took to organizing the others, so
the animals were ready when the time came. Then, on Midsummer's Eve (in June), Mr. Jones
got so drunk that he didn't come home until the next day. After arriving, he went right
to sleep without feeding the animals. One of the cows broke down the door to the shed,
so Jones' workers began "lashing out in all directions" with their whips. In one sudden,
unified rush, the animals attacked the men, who were "butted and kicked from all sides."
Mrs. Jones grabbed a few items and ran from the house, joining her husband and the
workers in the road, where the animals left them, slamming the gate behind
them.