People's Republic of China, Mao Zedong actively advocated for the use of irregular military tactics by regular military units. In his book On Guerrilla Warfare, Mao described seven types of Guerilla units, and argues that "regular army units temporarily detailed for the purpose (of guerilla warfare)," "regular army units permanently detailed (for the purpose of guerilla warfare)," and bands of guerillas created "through a combination of a regular army unit and a unit recruited from the people" were all examples of ways in which regular military units could be involved in irregular warfare. Mao argues that regular army units temporarily detailed for irregular warfare are essential because "First, in mobile-warfare situations, the coordination of guerilla activities with regular operations is necessary. Second, until guerilla hostilities can be developed on a grand scale, there is no one to carry out guerilla missions but regulars." He also emphasizes the importance for the use of regular units permanently attached to guerilla warfare activities, stating that they can play key roles in severing enemy supply routes. Effectiveness While the morale, training and equipment of the individual irregular soldier can vary from very poor to excellent, irregulars are usually lacking the higher-level organizational training and equipment that is part of regular army. This usually makes irregulars ineffective in direct, main-line combat, the typical focus of more standard armed forces. Other things being equal, major battles between regulars and irregulars heavily favor the regulars. However, irregulars can excel at many other combat duties besides main-line combat, such as scouting, skirmishing, harassing, pursuing, rear-guard actions, cutting supply, sabotage, raids, ambushes and underground resistance. Experienced irregulars often surpass the regular army in these functions. By avoiding formal battles, irregulars have sometimes harassed high quality armies to destruction. The total effect of irregulars is often underestimated. Since the military actions of irregulars are often small and unofficial, they are underreported or even overlooked. Even when engaged by regular armies, some military histories exclude all irregulars when counting friendly troops, but include irregulars in the count of enemy troops, making the odds seem much worse than they were. This may be accidental; counts of friendly troops often came from official regular army rolls that exclude unofficial forces, while enemy strength often came from visual estimates, where the distinction between regular and irregular were lost. If irregular forces overwhelm regulars, records of the defeat are often lost in the resulting chaos.