With French, Belgian and Portuguese activity in the lower Congo River region undermining orderly incursion of tropical Africa, the Berlin Conference of 1884–85 was held to regulate the competition between the European powers in what was called the "Scramble for Africa" by defining "effective occupation" as the criterion for international recognition of territorial claims. The scramble continued into the 1890s, and caused Britain to reconsider its decision in 1885 to withdraw from Sudan. A joint force of British and Egyptian troops defeated the Mahdist Army in 1896, and rebuffed a French attempted invasion at Fashoda in 1898. Sudan was nominally made an Anglo-Egyptian Condominium, but a British colony in reality.