Question

despite a smaller army, how was tokugawa leyasu able to win the battle of sekigahara? by convincing some of his opponents allies to switch sides be retreating during the battle and regrouping his forces by receiving reinforcements from neighboring countries by developing weaponry powered by solar energy

Explanation:

Tokugawa Ieyasu won the Battle of Sekigahara mainly by convincing some of his opponent's allies (like Kobayakawa Hideaki) to switch sides. This strategic move weakened the opposing coalition. There was no retreat and regrouping as described in the second option that led to victory. Japan at that time was in a feudal - like state with no significant reinforcements from "neighboring countries" (it was more of internal daimyo - based politics). And solar - powered weaponry was not a factor in 17th - century Japan.

Answer:

By convincing some of his opponent's allies to switch sides