The German-language website already mentioned has a section devoted to eyewitness accounts about the siege and life in the camps. It seems worthwhile to share a few details from some of them:
In his lively account of leaving Shanghai, Bodo von Gimborn relates that some people took tennis rackets and evening dress with them to Tsingtao, expecting almost to be on holiday.
Eduard Lendrich describes a standoff in the station in Tientsin, in which the German troops travelling from the garrison in Peking to Tsingtao were confronted by French troops on the platform. The quick thinking of the German chief engineer of the railway company saved them by taking over control of the engine and driving the train right out of the station.
Erich Kaul was a stoker on SMS Jaguar, a German gunboat which travelled up the Yangtze to Hankow (now a part of Wuhan) shortly before the outbreak of war. The ship managed to return to Tsingtao in time to take part in the defence of the town. Kaul’s early account is engaged and interesting, but his health and morale clearly suffered during his subsequent imprisonment.
In his account Adalbert Freiherr von Kuhn discusses Bushido, the Japanese code of honour. When the German officers complained about their treatment to a Japanese officer, he replied by asking them why they had not shot themselves rather than surrender. He then relates how a Japanese officer committed suicide because he felt that he had failed in his duty during the siege of Tsingtao.
Rudolf Fischer was transferred to Bando in 1918, so his account augments the information to be found in Die Baracke.
Jakob Neumaier wrote a comprehensive, insightful and balanced account of both the siege and his subsequent internment.