'On that Day' in the Bible

On that day Deborah and Barak son of Abinoam sang this victory song:

then they said to him, "Say 'Shibboleth!'" If he said, "Sibboleth" (and could not pronounce the word correctly), they grabbed him and executed him right there at the fords of the Jordan. On that day forty-two thousand Ephraimites fell dead.