He rendered service to the Tokugawa in a number of significant ways, including contributing forces to the Osaka Castle campaigns, and corvée labor to the construction of the shogunal cities of Edo, Sunpu, Nagoya, Shinoyama, and Fushimi, and to the reconstruction of Osaka following the campaigns. He also contributed warriors to help shogunal forces effect the confiscation of Fukushima Masanari's domain of Hiroshima han in 1619. These expenses, combined with the steep costs of sankin kôtai, drove Tosa domain deep into debt as early as the 1620s, to such a point that they had difficulty finding Edo or Osaka merchants willing to lend to the domain.
The grievous financial situation of the domain reached a crisis point in 1620, when Tadayoshi was told by shogunate officials that he was in danger of having his domain confiscated. Yamauchi retainers, deeply loyal, offered to have the lord confiscate their sub-fiefs, in order to help him cover the domain's costs; Tadayoshi did not take that step, but asked his retainers for 25% of their incomes to help pay off the domain's loans. This was, however, nowhere near sufficient. Tadayoshi then imposed new corvée obligations for the peasantry, dramatically expanding lumbering efforts; though some of his advisors worried this would work the peasants too hard, taking them away from the fields and thus away from growing crops, or inspiring peasant uprising or exodus, the scheme worked. Before long, vast amounts of lumber from Tosa was piling up and being sold in Osaka markets, and the domain repaid all of its loans. Tadayoshi then secured an agreement with the shogunate that in future Tosa would be able to contribute lumber, rather than labor, in fulfillment of feudal obligations to contribute to shogunate construction projects.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005
- Luke Roberts, Mercantilism in a Japanese Domain: The Merchant Origins of Economic Nationalism in 18th-Century Tosa, Cambridge University Press (1998), 52-55.
- Luke Roberts, "Cultivating Non-National Historical Understandings in Local History," Joshua Fogel (ed.) The Teleology of the Nation-State, Univ of Pennsylvania Press (2004), 167.