The Rebbe only missed one Sunday Lag B'Omer parade ever: in 1973, the year that we are studying. We know that The Rebbe refused to attend, and we know that he delivered a Sicha describing his reasons, but the details remain opaque. In this letter The Rebbe responds to a Chosid protesting his decision, with guidance deeply applicable to modern Lag B'Omer parades. The class reviews the Sicha in question, and provides a brief history of the parades.