This series of articles will delve into the key historical events that unfolded during the month of April. We will explore the formative years of the game, examining crucial league meetings and the establishment of foundational principles. We will analyze landmark rule modifications implemented in April that have had a lasting impact on gameplay. Furthermore, we will revisit notable player drafts, trades, and signings that occurred in this spring month, forever altering the trajectories of franchises and the careers of iconic athletes. Join us as we uncover the hidden history of American football within the springtime of April, revealing the significant milestones that occurred away from the traditional spotlight of the regular season.