I just found this photos on the web.
Stephen Turnbull's Battles of the Samurai and Sadler's Maker of Modern Japan are your English best choices so far. I have been to the battlefield once in 2001. I plan to go again in the future. I do plan to write about Lamers's opinion on Nobunaga's use of the "Tenka" Monday or Tuesday.
Tenka no tame!