Following a period of great spiritual growth and national rescue, the Israelites experience a tragic downfall that plunges them into a harsh era of slavery. The death of the prophetess Deborah marks a turning point where the nation abandons its faith, triggering a prolonged period of foreign oppression.
In the past, the nation's rebellions were characterized as a continuation of bad behavior, pointing to a steady pileup of sins. Now, however, their actions are viewed as a completely fresh start of wrongdoing. This change highlights a major spiritual reset that occurred during Deborah's leadership. In her days, the Israelites achieved complete repentance. Through the merit of the Song of Deborah, God forgave all their previous wrongdoings. Because their slate was wiped clean, their current turn away from the right path is treated as an entirely new beginning of sin, rather than an addition to past failures [רש״י, מלבי״ם, אברבנאל].
As a direct result of this fresh rebellion, God places the nation under the control of Midian for seven years. This period of subjection is marked by extreme suffering. The grip of the Midianites is so overpowering that the Israelites are forced to abandon their homes and seek refuge in mountain caves and hidden strongholds. The oppression extends beyond physical control into total economic devastation. The Midianites and their allies routinely invade to destroy the crops just before they can ripen. They loot the livestock and strip the land of its resources, leaving the Israelites without any means of survival [אברבנאל].