Wildland fire involves both chemical and physical processes. In the burning of wildland fuel burns, their stored chemical energy is converted to thermal energy or heat through a series of complex chemical reactions. But for the combustion process to be started, heat must be physically transferred from a firebrand to the fuel, and heat transfer to unburned fuel must continue if the fire is to keep on burning and spreading. Control and extinguishment of a wildland fire hinges upon the interruption of the chemical reactions. And about the only way we have of doing this is by reducing or eliminating heat transfer. In earlier publications, we explored the nature of heat and the process of heat transfer by conduction. In the following discussion, we will look at the combustion process and the part that heat conduction plays in it, and how heat transfer by conduction can be checked in fire control operations. All three methods of heat transfer-conduction, radiation, and convection-are usually operating at the same time in a wildland fire. But radiation and convection can transfer heat only to the fuel surface. The only way that heat can get into the interior of opaque materials like wildland fuels is by conduction. Hence, conduction of heat is of major importance in the combustion process, particularly for the larger fuels. The level of difficulty of the treatment of topics in these publications varies, as signaled by the color of the cover: the blue cover group is generally elementary and the yellow cover group is intermediate.