Taupaca dropped down heavily on a small rock. His officer had graciously allowed the squad a five minute break. They had been training furiously for two weeks now with barely any time to rest. The net result of this was that not only was he tired to the point of collapsing, but so was the rest of the 6-man unit.
Taupaca did not know what they were training for. He had been chosen as the only one from his old platoon for what was only called special duty. After the choosing he had gone to a camp deep in the Andes where he joined about 300 other soldiers. Some wore black uniforms with no markings apart from some unknown insignia, but others, like him, wore standard army uniforms.
For four days they had been forced to move a pile of rocks from one end of the camp to another with only minimal breaks. Throughout all of the time none of the black-clad troops had spoken for them for those days. He wondered why they were forced to move those rocks about. It made little sense to him. Some of the others from his new squad had tried to argue against it, but the only thing that accomplished was that the man they only knew as "sergeant" had knocked them to the ground, told them that it was the will of the Sapa-Inca and to just shut up and do as he was told.
After moving rocks for eight days he was more tired than he had ever felt before, but he was forced to admit that what was at first an amazing hard task had grown easier as they got stronger. After they managed to move the pile of rocks in about 3 hours the sergeant had nodded and said "good enough", whatever that meant. Taupaca just knew that he hadn't had to move a rock since then. After that they were moved to another part of the camp where they were given wooden swords and daggers and told to defend themselves. A squad of blackclad soldiers had attacked them with identical weapons and in less than five minutes Taupaca and the rest of his squad lay groaning on the ground. Shaking his head in contempt the sergeant had ordered them up and told them to do better. That day Taupaca found himself knocked down more times that he could even remember.
Next day was more of the same, but with an important difference. Now they actually had a guy there instructing them. While they still lost every time they were attacked they managed to stay on their feet longer than before. Gradually as the days went by they got better and better. The intensity of the training was intense and they spent practically all of the day from sunrise to sundown training. Finally, the day before, the sergeant said it was enough and that it had to do for now. Thoroughly exhausted, but also much fitter than they were just two weeks earlier, the squad had fallen asleep only to be woken up before sunset.
They had now been on the trail for half the day. Where they were going nobody knew and the sergeant wasn't telling. As he sat on the rock Taupaca wondered why they were being drilled so hard. It was obviously part of the army, but it was no unit he had ever heard of and the training was unbelievable. Closing the eyes for a minute he jumped surprised to his feet as the canyon suddenly echoed with battlecries and he saw a large group of men rushing toward him. Within seconds the first was upon them and he had to defend himself. Striking out he heard a bone break close by as he incapacited his own direct opponent. After what seemed like hours, but was really only minutes, the last of the attackers lay on the ground. Looking around he saw all of his unit was still standing while 20-30 attackers lay dead, unconscious or stunned on the ground. Looking at his sergeant he saw something completely unexpected. For the first time ever the man had a grin on his face and was nodding appreciatively. Looking from one man to another he smiled with pleasure.
Crossing his arms over his chest he spoke and, for once, there was no coldness in his voice. The words he said shocked Taupaca: "You are now ready to begin your training."
As they marched back to the camp Taupaca learned that the attackers were a group of smugglers and bandits that had been haunting the region and rather than just having the army deal with them it was decided to use it as a test for his squad.
When they came back to the camp they were all given black uniforms to replace their old, worn ones, with only the difference that their uniforms had a white condors head on it signifying that they were still in training. At long last they were told what was happening. They were a new special unit in the Incan army whose role would be much different from the regular troops.
Their role would be to protect Peru from invaders by causing avalanches, poisoning enemy foodsupplies and operating behind enemy lines to cause chaos and thus make it impossible for an enemy army to survive in the mountains. Also, they were to serve as infiltrators and scouts in case the Incan army ever went on the offensive. They would be the elite of the army. Few in numbers, but with skills enough to make up for it. They would be named for the colour of their uniforms and their stealth. The were the Black Ghosts.
OOC: New UU in case you are wondering das

Kind of like an early US Delta Force/UK SAS unit/Russian Spetsnaz, just with training and equipment matching the time period. Role is much the same though.