Read this article and answer this question Both sides had forces that did not arrive at Sekigahara in time to participate due to other battles.  Ieyasu's son Hidetada led another group through Nakasendō. However, Hidetada's forces were bogged down as he attempted to besiege Sanada Masayuki's Ueda Castle against his father's direct orders. Even though the Tokugawa forces numbered some 38,000, an overwhelming advantage over the Sanada's mere 2,000, they were still unable to capture the strategist's well-defended position. At the same time, 15,000 Toyotomi troops were being held up by 500 troops under Hosokawa Yūsai at Tanabe Castle in present-day Maizuru, Kyoto Prefecture. Some among the 15,000 troops respected Hosokawa so much they intentionally slowed their pace. Due to these incidents, a large number of troops from both sides failed to show up in time for the battle. If either of these armies participated in the conflict, it could have ended quite differently.
How many troops were at Tanabe Castle?
15500