Yes, you were under a lease agreement and yes, you are required to give written notice.
In most states 30 days. In some states less. As I recall MD is 30 days (two months in Montgomery County and Baltimore City).
That said, I am not MD attorney, you should contact a MD attorney to review your rights or liabilities.
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You were required to give notice. Check your lease for the length of the notice required (i.e. 30 days; 60 days). Not only were you required to give notice, it was likely that it had to be delivered before the first of the month.
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