Dozens of recently-discovered letters handwritten by Siegfried Grabert portrays some early undertakings of Germany’s elite warrior spies – The Brandenburg Commandos – in World War II.

The letters were discovered in Malta by the descendents of a Maltese soldier who had served in Germany during the war.

Writing to his brother Gerhard on 2 June 1940, Hauptmann Grabert reveals how he managed to storm and seize the bridge at Nieuport in Belgium with only a few men. The successful operation was pivotal for the Germans as it enabled their armoured divisions to advance into France.

Grabert, who was a highly decorated Major of the reserves in the Wehrmacht, was also a recipient of the Knight's Cross of the Iron Cross with Oak Leaves – awarded to recognise extreme battlefield bravery or successful military leadership.

Grabert was killed on 25 July 1942 during a commando operation to destroy a dam between Rostov and Bataisk. He was posthumously promoted to Major der Reserve and on 6 November 1943 was awarded the Oak Leaves to his Knight's Cross.

Independent German, Belgian as well as French academics describe the surviving Siegried Grabert dispatches “a significant find”. The letters written in Sütterlin, the historical form of German script, await transcription.