[1]During the Diponegoro War (1827-1830), Colonel Hoorn, Commander of the 2nd Division, assigned to the crossroads at Bawen, instructed the construction of a logistical supply point, as well several military barracks, to give immediate supply and forces for the war, as Bawen is a vital junction connecting the cities of Semarang, Yogyakarta, Salatiga and Surakarta.
In 1840, Ambarawa had become a strategic military outpost, serving as a choke point between Semarang and Surakarta.
Their purpose was to establish a relationship with the Sultanate of Mataram and to prevent native troop movements.
The private Dutch East Indies Railway Company (NIS) received concession in 1862 to build a rail track connecting Semarang, Surakarta, Magelang and Yogyakarta with a branch toward Fort Willem I.
[1] In 1927, Fort Willem I changed its function from a juvenile penitentiary into an adult and political prison.