In 1911, while he was still a teenage boy, Mandume became leader of the powerful Kwanyama kingdom in Owamboland in what is today northern Namibia. Although he only ruled for six years, he is respected as a leader of resistance against colonial intrusions.
At the time that he became king, Kwanyama territory was under pressure from the colonial powers that were operating in the region. The immediate threat came from the Portuguese in Angola, who already claimed the largest, northern part of Kwanyama territory by agreement with the Germans. The latter claimed a protectorate over Owamboland up to the Portuguese border, even although they did not have a presence in the territory. In 1915, the pressure increased when the South Africans conquered German South West Africa on behalf of the British Empire and made it plain that they intended to intervene actively in Owamboland.
Mandume's position was not secure. Firstly, he was young and had already been the target of one assassination attempt. Secondly, he had to deal with an influential group of Kwanyamas who profited from trade with European goods, which came from colonial territories; they were therefore likely to be swayed as much by commercial motives as by loyalty to Mandume. Even his own uncle, who was influential in the royal family, was a member of this group. Thirdly, the idea of ‘a tribe' was not as fixed and inflexible as it is sometimes portrayed by outsiders. Headmen, who were the intermediaries between the king and the majority of the population, could quite easily switch allegiances to secure greater advantages for themselves.
One of Mandume's greatest concerns was the fact that the Portuguese were replacing hereditary chiefs with their own headmen who were loyal to them, thus weakening the control of the traditional leaders. Another of Mandume's concerns was the spreading influence of the church and the missionaries, which he regarded as agents of the penetration by colonial powers. Accordingly, he burned down a Roman Catholic mission station, expelled the occupants, and made life difficult for the other missionaries within his territory. He also prevented the Portuguese from gathering taxes in the part of his territory that they controlled. Actions such as these made him unpopular with the colonial authorities, who rightly perceived Mandume as an obstacle to their plans for hegemony over the parts of Owamboland that they claimed. In fact, by 1911 Mandume was the only remaining independent ruler in southern Angola as the Portuguese had conquered all the others.
One of Mandume's major strategies to strengthen his position was to curb the independence of headmen by regularising the taxes that were paid in cattle - the major store of wealth - as well as ensuring that all judicial cases involving cattle were directly under royal supervision, thus reducing the ‘protection money' that the headmen received and, in so doing, strengthening the king's central control. These measures also created internal enemies who could easily switch their allegiances if advantages seemed to beckon elsewhere.
When the First World War broke out in 1914, Mandume seized the opportunity to ally himself with the Germans against the Portuguese. However, this attempt failed when the German force, supported by some of Mandume's men, was defeated by the Portuguese. Nevertheless, Mandume achieved enough military success against the Portuguese for him to become an embarrassment to them. In consequence, they sent a large force of 600 to 7000 white soldiers against him - a very considerable force in that context. Mandume retreated to the southern part of his territory, which lay beyond the Portuguese border. Now he made contact with the South Africans, the new power in South West Africa, who sent word that they would offer him protection if he agreed to remain within the southern part of his kingdom and not cross the border into Portuguese-claimed territory. Mandume agreed to abide by this arrangement.
However, this situation caused a power vacuum in the northern part of the Kwanyama kingdom, because the Portuguese could not exercise real authority there and Mandume was unable to do so. In fact, the local people accused the Portuguese troops who were present in the border areas of being responsible for banditry and looting. To deal with this situation, Mandume made a number of trips across the colonial border. These violations of the agreement angered the South Africans, who thought that Mandume was acting provocatively, while the Portuguese chose to describe them as ‘cattle raids'.
The crunch came when Mandume again ventured northwards to protect a headman who was expecting an attack by the Portuguese. In the ensuing clash, Mandume's force inflicted an embarrassing defeat on the colonial soldiers, who retreated in disarray. The Portuguese responded by sending an even larger force, better armed and better equipped, which Mandume also defeated by using guerrilla tactics to nullify the effect of the Maxim guns and motor vehicles. His success alarmed both colonial powers, who now clearly perceived that Mandume was the greatest obstacle to their expansionist plans.
The South Africans began to prepare for Mandume's demise by subverting as many headmen as possible with promises of benefits, such as cattle, land, and titles, if they would loosen their allegiances to Mandume. This strategy worked well and weakened Mandume's power. Finally, during February 1917, a strong South African force moved against Mandume, guided by informers and taking care to avoid the guerrilla-like traps that Mandume had laid for them. By outflanking the opposition, when the force approached Mandume at his homestead, he had less than 300 men with him. There was a furious exchange of gunfire until the Maxim guns opened up, killing Mandume and settling the conflict decisively.
The outcome was disappointing for the headmen who had taken the side of the South Africans. Not one of them was made king; instead, the South African authorities declared that the position would remain vacant, with the royal powers being exercised by the colonialists. Crucially, headmen would receive incomes that were calculated according to how many men they sent southwards to work as migrant labour. In fact, Owamboland was viewed as a perpetual economic backwater that had only one useful purpose in the colonial economy, namely the supply of labour. Thus, with the death of Mandume in 1917, a pattern was established that lasted almost until Namibia became independent in 1990 - and was, in fact, a major cause of the liberation struggle.