HistoryData
war1945

Battle between Indonesian and Allied forces during the Indonesian National Revolution

December 15, 1945

One of the most successful Indonesian offensives of the National Revolution, it confined British and Dutch forces to Semarang city and established the date of Indonesian National Infantry Day.

Quick Facts

Year
1945
Category
war

Key Facts

Overall duration
20 Oct 1945 – 2 Mar 1946
Battle of Ambarawa duration
55 days days
Magelang offensive duration
49 days days
Region contested
Semarang, Semarang Regency, Magelang Regency
Indonesian National Infantry Day
15 December (commemorates this battle)

By the Numbers

20
Overall duration
55days
Battle of Ambarawa duration
49days
Magelang offensive duration
15
Indonesian National Infantry Day

Location

Map of Semarang, IndonesiaMap of Semarang, IndonesiaSemarang, Indonesia

Cause → Event → Consequence

Cause

Following Indonesia's declaration of independence in August 1945, the newly formed Indonesian Army sought to resist reimposition of colonial control by British forces accompanied by Dutch troops in Central Java. Tensions escalated as Allied forces moved into the Semarang and Magelang areas, prompting Indonesian commanders to mount coordinated offensives.

Event

Between 20 October 1945 and 2 March 1946, Indonesian forces conducted a composite offensive comprising the Battle of Ambarawa, the Magelang offensive, the Battle of Ungaran, and the Semarang offensive proper. Fighting took place across Semarang city, Semarang Regency, and Magelang Regency in Central Java, pitting the fledgling Indonesian Army against British and Dutch forces.

Consequence

The offensive succeeded in driving British and Dutch forces out of the Magelang and broader Semarang metropolitan regions, confining their control to Semarang city alone. It became regarded as perhaps the most successful Indonesian offensive of the entire National Revolution, and 15 December was subsequently commemorated as Indonesian National Infantry Day.

Belligerents & Mobilization Analysis

Side A

1 belligerent

Indonesian Army (Tentara Nasional Indonesia)

Side B

2 belligerents

British ArmyDutch forces (NICA)
Outcome
Indonesian forces pushed British and Dutch control back to Semarang city; Indonesian strategic victory.

Timeline Context

Timeline around 194519451942194319441946194719481945 major battle of the Pacific War1945 battle in the Eastern Front of World War IIFinal World War II operations in Slovenia in May 1945.Treaty transferring territory between the United States and Soviet occupation zones of Germany after World War IIBorneo campaign — 1945 last major Allied campaign in the South West Pacific Area during World War IILasker Award — American medical science award2nd Golden Globe Awards — 1945 film award ceremony, on the 16th of April in Beverly Hills, California, United States of America, honoring achievements in 1944 filmmakingManila massacre — atrocities committed against Filipino civilians by Japanese troops at the Battle of Manilabattle-of-ambarawa-1945