The African Marathon
The war started with a race. Whichever side moved first would have a massive advantage in the war. However, both the Portuguese and North German armies in Africa didn't actually know that their nations were at war yet. Telegraph lines were incomplete and one couldn't simply tell the armies to attack the other with a simple call. Both the North German General Staff and the Portuguese realized that they needed to actually inform their armies of the war as soon as possible. As a result, the first few days of the Luso-North German War was a frenzied dash by Portuguese and North German officials to actually get the word out to their respective armies. Telegraphs would have to go as far as they could get - and then frenzied colonial officials would have to move as quickly as they could in order to get to the next set of telegraph stations with the message. Several officials involved would eventually choose to become sportsmen instead, having displayed alternative skills beyond colonial administration in biking, swimming, and running across Africa.
Unironically, one historian argues that Portugal's relative poverty would prove decisive. Namely, Portuguese officials stopped for meals less often than their North German counterparts, having been accustomed more to skipping meals and overly warm weather. As a result, the Portuguese Army was the first to ultimately be informed that the war was actually on. This proved quite disastrous for the North German Army that had surged into Portuguese Africa in pursuit of Herero refugees - they quickly found themselves deep in Portuguese territory and under attack by the Portuguese. Surrounded, out of supplies, and in unfamiliar land, the North Germans in Portuguese Africa quickly surrendered, a huge blow to North German operational defenses in North German Southwest Africa.
This left a huge imbalance in terms of military capacity between the Portuguese and North Germans in Namibia. Namely, Southwest Africa had roughly 19,000 North German troops, as German East Africa only had roughly 9,000 troops, both including settler militias. The Portuguese had roughly 12,000 troops in both Angola and Mozambique, but events were to turn heavily against the North Germans in both front. Namely, North German rule in Tanganyika had grown to be detested by locals. The North Germans ordered local villages to pay taxes in cotton, a crop that did not normally grow in the region, which forced massive disruptions onto the native way of life, causing massive poverty and outrage. After a local folk Islamic shaman claimed that he had magic war medicine that could ward off North German bullets, Portuguese colonial officials quietly slipped him large amounts of actual rifles to aid. Local Sufi Muslims quickly declared a "jihad" against North German colonial officials, as North German fortresses found themselves under siege by tribal warriors. This rendered the German garrison in East AFrica utterly useless for the actual war against Portugal, leaving the actual North German Army in Namibia the only meaningful threat - a threat that had already lost much of its manpower along the Portuguese Zambezi.
The Ottomans notably refused to lend support for the rebels - but a different power did, infuriating the North Germans. Napoleon V, the crown prince of Imperial France, had been educated as a young child by one of the Sufi sons of the late Emir Abdelkader. The younger Crown Prince convinced his notoriously aggressive father, Napoleon IV, to sign onto a declaration by various Sufi leaders in Algeria (which whom both he and his father had built excellent relations with in the 1870's thanks to the Emir Abdelkader) declaring support for the Sufi-led revolt, praising their dedication to Allah. Critics of the Ottoman Empire surprisingly found the French Emperor, who had acrimonious relations with the Ottomans and still claimed to be the "Protector of the Holy Land", a better alternative over the Ottoman Sultan, a fact that Napoleon IV caught on when he appended "Protector of Islam" to his list of titles. King Wilhelm II notably called Napoleon IV a race traitor and a "embarrassment to the descendents of Charles Martel" in response, a phrase that was repeated by some anti-monarchy activists. The rebellion in East Africa was probably the worst of all of the rebellions in the North German colonies. The Governor of North German East Africa, Count Gustav Adolf von Gotzen, embarked on a campaign to simply win the rebellion by deliberately starving the natives to death, but they simply fled into Portuguese lands and returned with a grudge and weapons. The Portuguese didn't actually want them to succeed and didn't even oppose the North German famine campaign, but they figured it would at least keep them busy, which it did.
The Portuguese correctly assumed that troop transports could come from North Germany to the Congo and Namibia faster than it could to Eastern Africa, so those two were immediately treated as the priority. Cabinda was a high profile port for Portugal, with one of the largest garrisons. That garrison simply marched into Matadi, the only port into the North German Congo, garrisoning the city and capturing the small garrison. Although the Portuguese hoped for a rebellion in the North German Congo, it never actually happened, but fearful of one, North German garrisons also refused to vacate their posts. Regardless, the North German army in Central Africa seemed tied down as well. With two triumphs under their belt, they decided to strike the final blow to the North German colonial empire in Namibia.
Walvis Bay was under British control - and so the primary seaport into Namibia was Luderitzbucht in the south. This presented a serious dilemma for the Portuguese, because they didn't actually have an easy way to reach the port city. They could march into Namibia and overwhelm the North Germans with sheer numbers (which they did begin to do, albeit with massive casualties against wily North German foes), but there was no evidence they could actually reach Luderitz. Thus, an offer was made, without the knowledge of Lisbon. In the Dorsland Trek, several Boers who grew angry over the "surrender" of the Boer Republics to British domination (as de facto British colonies) without a fight simply left the Boer Republics, hoping to create a "new Boer Republic." Many made their way to Namibia, which they found to their distress was eventually put under German rule. German rule was fairly kind to the Boers (and extremely harsh to the natives), but the Portuguese made the Namibian Boers a deal they couldn't refuse - an independent Boer state in Namibia. A small population of such Boers had landed in Portugal and had chafed under Portuguese administration - and they jumped at the deal.
A squad of Boer commandos, paid by the Portuguese, simply snuck into Luderitz under the cover of night. Breaking open the concentration camps and handing the natives weapons, they just told them to make havoc (the Boers had low opinions of the natives, but thought them useful). In the chaos, they simply destroyed the port of Luderitz, tossing mines and wreckage all over the port bay, an already very inhospitable bay. German forces in Namibia were left without an easy way to ferry in supplies and reinforcements, except very slowly. However, their superior military training and firepower meant massive Portuguese losses when the Portuguese attempted an ill-fated offensive. However, when organizing troops for a push to encircle and wipe out the Portuguese, a problem arose. The Herero weren't the only ones furious with North German rule. The Namaqua, one of the oldest of the Khoi peoples (in contrast to the Bantu Hereros) were generally seen as less threatening by the North Germans who rated the Khoisan peoples even lower in their racial hierarchy than the Bantu, which meant the Namaqua revolt had come as a total shock to the North Germans. Portuguese smugglers rapidly gave them weapons, forcing North German troops to land the final blow against the Portuguese, pulling away from the frontline to deal with the crisis.
Nama troops were obviously no match for the vastly superior North German troops, but with the port in Luderitzbucht wrecked (requiring several weeks to rebuild), supplies and reinforcements could only trickle in at a relatively slow rate from hastily made makeshift ports. The North German general staff was starting to realize something very unfortunate for them. They planned on destroying the entire Portuguese Army in Angola and Mozambique, using it to overrun all of their African colonies and establishing a true dream of Mittelafrika. However, the Portuguese, while taking horrendous losses that significantly outstripped North German losses, had managed to be more tenacious than expected. The North Germans were basically on the defensive in East Africa, Central Africa, and Southwest Africa. The war plan was an absolute failure. North Germany had mastered the art of maneuver warfare in Europe, but they had no experience in fighting a multicontinental war, ferrying troops around the world. Commander von Trotha proved to be actually incompetent in combat, and their most competent commander, Paul von Lettow-Vorbeck, had taken massively numerically inferior and poorly supplied German troops had put down the Nama revolt, before being shot in the shoulder (and evacuated for medical treatment) by Jacob Morenga, the charismatic "black Napoleon" leading Nama troops. Morenga's moniker pleased the French Emperor, who sent a telegram congratulating Morenga, further infuriating public opinion in North Germany against the French.
King Wilhelm II was not very happy when the North German General Staff notified him that an easy victory would not happen in Africa. They could spend several months ferrying troops into East Africa, put down the Islamic rebels, and from there sweep into Central Africa - and then finally from there sweep into Angola and crush the Portuguese. They estimated that this would take at least three years, most likely longer, and that it was probably easier suing for peace than grinding this war out, which saw commerce avoid both Portugal and North Germany. Wilhelm II was furious. That was not the answer he wanted. He promoted instead one of the most hawkish members of the North German General Staff, one of the newest members (only promoted in 1904), Erich Ludendorff, who promoted an alternative, much more aggressive, much faster strategy that would punish the supposed "Lusitanic race traitors" (the Portuguese did not think very highly of the natives either, even if they were willing to use them against the North Germans).