After a remarkably brief campaign during February to March 1942, the Japanese occupied virtually all of modern-day Indonesia. The biggest shock for the Allies had been the fall of the “impregnable fortress” of Singapore in mid-February 1942. From that point on, the Dutch knew that Java was gravely threatened and that they could lose their entire colony. Indeed, some already thought that their situation was hopeless. They had already lost most of their naval forces in the Java Sea action.

Hamengku Buwono, in what seems to have been his first ever radio address to his subjects, admitted the seriousness of the situation “although it is in no sense hopeless”. He advised the people of Yogyakarta to ignore stories that the enemy could not possibly reach Java, and called for a “realistic” attitude. The people should take appropriate security measures and follow the instructions of relevant official agencies, such as the Red Cross. He added that he had no wish to spread alarm, but needed to point out the gravity of the situation.

In their feverish preparations to defend Java, the Dutch colonial leaders quickly concluded that comprehensive defence of the island was impossible with the forces at their disposal. The naval commander, Admiral Helfrich, contended that the main naval base, Surabaya, above all should be held, but the army commanders favoured West Java for the main troop concentration. Eventually the Governor General decided on 22 February to concentrate his forces in both East and West Java, and that “only Central Java should be largely denuded of forces, although that was also regarded as risky because of possible unrest in the princely states”. The relevant division Commander, Major General Cox, protested “because of the unfortunate effect on the Javanese princes and the people … this means no less than a useless end to the so fruitful three hundred years of Netherlands Government”.

The Java princes were probably not informed of Dutch strategic planning, but the absence of Dutch defenders around Yogyakarta must have been evident to everyone. Therefore, Hamengku Buwono was aware that the Dutch had abandoned Yogyakarta to the Japanese; and General Cox may well have been right in his assessment of the effect on the attitude of this particular Javanese prince.