Classic and modern theories of rebel warfare emphasize the role of resource endowments. We demonstrate that intelligence gathering, made possible by these endowments, plays a critical role in determining specifics of how rebels launch complex attacks against better equipped government forces. We test implications of a theoretical model using highly detailed data about Afghan rebel attacks, insurgent-led spy networks, and counterinsurgent operations. Leveraging quasi-random variation in opium suitability, we find that improved rebel capacity is associated with (1) increased insurgent operations; (2) improved battlefield tactics through technological innovation, increased complexity, and attack clustering; and (3) increased effectiveness against security forces, especially harder targets. These results show that access to capital, coupled with intelligence gathering, meaningfully impacts how and where rebels fight.