In the early period of the war, he led to victory the battle to defend guerilla zones from March 1934 to March 1935.

The battle was characterized by the close combination of defensive fight and harassment operation behind enemy lines.

The battle put an end to the siege operation of the enemies, making contributions to the accomplishment of strategic tasks for the first-stage of the anti-Japanese revolutionary war to preserve and train the revolutionary forces including the Korean People's Revolutionary Army and spread and develop the armed struggle.

At a meeting held in Nanhutou, China in February Juche 25 (1936), Kim Il Sung advanced a strategic line to conduct mobile guerilla activities with large units, a reflection of lawful requirement of the developing Korean revolution in the latter half of 1930s.

According to this line, the KPRA units carried out many mobile operations like the march into the area of Mt. Paektu, guerilla activities in the southwestern area of Mt. Paektu and advance into the homeland, weakening the strength of the enemy with continued battles. Typical of them is the battle of Pochonbo, which has been well-known over the world.

In August 1940, he convened the Xiaohaerbaling Meeting at which he set forth the strategic line to conduct small-unit guerilla activities.

The line made it possible to preserve and further strengthen the revolutionary forces as part of preparations for liberating the country.

In particular, the final offensive operation for the liberation of the country led by Kim Il Sung was a superb guerilla operation which successfully brought the anti-Japanese revolutionary war to a finish.