user: Question: What was the date of the game against Northwestern?
Columns: ['Date', 'Opponent', 'City', 'Result', 'Score']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['September 19', 'Kansas', 'Lawrence', 'Win', '61-0']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Opponent" = 'Northwestern';