|Battle of Jassin|
|Part of the East African Campaign of World War I|
|Commanders and leaders|
|Paul von Lettow-Vorbeck||
Raghbir Singh †|
Captain J.G.J. Hanson
Captain J. Turner
23 machine guns
4 field guns
1 Town-class light cruiser
|Casualties and losses|
The Battle of Jassin (also known as the Battle of Yasin, the Battle of Jasin, the Battle of Jasini or the Battle of Jassini) was a World War I battle that took place on 18– 19 January 1915 at Jassin on the German East African side of the border with British East Africa between a German Schutztruppe force and British and Indian troops. Jassin had been occupied by the British in order to secure the border between British East Africa and German territory, but was weakly defended by a garrison of four companies of Indian troops, commanded by Colonel Raghbir Singh  and numbering a little over 300 men. Colonel Raghbir Singh was killed during the battle.
The German commander, Paul Emil von Lettow-Vorbeck, decided to attack Jassin in order to prevent further danger to Tanga, which lay more than 50 kilometres to the south and had previously been successfully defended against a British attack. Nine companies of Schutztruppe with European officers were gathered for the assault.
Immediately after the British force surrendered, British Captains Hanson and Turner were taken to see Lettow-Vorbeck. He congratulated them on their defence of the town before releasing them on the promise they would play no further part in the war.
Brigadier-General Michael Tighe arrived too late, just hours after the surrender to support the British at Jassin. Although the British force surrendered, Lettow-Vorbeck realised that the level of German losses of officers and ammunition meant that he could rarely afford confrontation on such a large scale and would need to make use of guerrilla warfare instead—he turned his attention away from seeking decisive battle against the British, concentrating instead on operations against the Uganda Railway. The British response was to withdraw and concentrate their forces in order to reduce their risks and make defence easier. As a result, the invasion of German East Africa was postponed for some time.
- Geographical names, "Jasini: Tanzania", SOURCE: National Geospatial-Intelligence Agency, Bethesda, MD, USA, accessed 30 March 2017
- Lettow-Vorbeck, Paul. My Reminisces of East Africa. London: Hurst and Blackett. p. 105.
- Paice, Edward (2007). Tip & Run - The Untold Tragedy of the Great War in Africa. London: Weidenfeld & Nicolson. pp. 79 to 84. ISBN 9-780297-847090.
- Paice, Edward (2007). Tip & Run - The Untold Tragedy of the Great War in Africa. London: Weidenfeld & Nicolson. p. 81. ISBN 9-780297-847090.
- Lives of the First World War, "Lifestory of Lieutenant Colonel Raghbir Singh Pathania" Archived 2019-02-20 at the Wayback Machine, Imperial War Museum, accessed 30 March 2017
- CWGC casualty record, "Casualty record for Lieutenant Colonel Raghubir Singh", Commonwealth War Graves Commission, accessed 30 March 2017
- Gaudi, Robert, author. (31 January 2017). African Kaiser : General Paul von Lettow-Vorbeck and the Great War in Africa, 1914-1918. ISBN 9780698411524. OCLC 957705214.CS1 maint: multiple names: authors list (link)
- Paul von Lettow-Vorbeck, My Reminiscences of East Africa, 63-64.
- Paice, Edward (2007). Tip & Run - The Untold Tragedy of the Great War in Africa. London: Weidenfeld & Nicolson. p. 84. ISBN 9-780297-847090.