The Germans after the agreement of 1886 proceeded with energy and determination not only to test the resources of their new "Colony," but to extend their territorial sphere in every direction--a proceeding which evoked a British protest and necessitated a fresh delimitation of boundaries in 1890. This was effected by the Caprivi Treaty of 1st July, 1890, under which Germany received ridiculously favourable consideration in every demand. In 1888 the whole of the remaining territory of the Sultan of Zanzibar on the mainland was placed under the administration of Germany by virtue of a lease from the Sultan. The new area included the magnificent harbour of Dar-es-Salaam, which became the principal port on that portion of the east coast. Five days after taking possession of the newly leased territory, the Germans managed to organise an "insurrection" amongst the natives; and the assistance of the Imperial (German) Government was invoked by the German East Africa Society to repress the "rebellion" which they had deliberately incited. Captain Hermann von Wissmann was at the beginning of 1889 accordingly sent out with full instructions to deal with the native revolt, and having enlisted a thousand or more ex-British _askaris_ (native soldiers) and Zulus, he proceeded to slay, burn, and destroy. A huge area was devastated and the "rebellion" was quelled, while the natives were thoroughly terrorised. The principal sufferers, however, were British Indians, owners of plantations and trading stations, and these fled for protection to British territory or crossed to Zanzibar. The German East Africa Company was severely censured in various quarters in connection with the "insurrection," but pleaded that it was a movement organised by the Arabs through jealousy at the success of German trading stations. This was credulously accepted by Great Britain, who went to the length, when her co-operation was sought by Germany in her need, of dispatching a fleet which united with the German ships in establishing a blockade all along the coast in Zanzibari waters. The Reichstag voted the sum of two million marks "for the suppression of the slave trade and the protection of German interests in East Africa," and this sum was used to meet the expenses of the "campaign." So far from expending millions of marks on the cause of humanity, the Germans, on their own admission, were largely employing slave labour on their tobacco plantations. The natives were not finally terrorised into submission until late into the year 1890; and the Germans, being firmly established, made their position unquestionably secure by purchasing from the Sultan, in the name of the German East Africa Society, the whole of his territory on the mainland for the sum of four million marks--only a part of which was, however, ever paid.