Yankee Warhorse is the first full biography of Osterhaus, who was probably the most successful, if most obscure of the dozen or so Union "German" generals.  

While the author, his several times great-granddaughter, independent scholar Townsend, occasionally gives him a break, she is by no means uncritical.  She picks up Osterhaus' story with some comments on the family roots and the general's immediate background in a middle class environment in the Rhineland, then goes on to discuss his service a volunteer officer in the Prussian Army and later command of liberal volunteers in Baden during the '48.  With the collapse of the liberal revolution in Germany, like so many others, Osterhaus fled to the U.S., and prospered in business in Missouri.  On the outbreak of the Civil War, he enlisted as a volunteer private, but rather quickly became an officer and then rose fairly steadily to major general by dint of battlefield skill.  As with many generals who served exclusively in the West, despite considerable success he tends to be overlooked. Townsend also notes that his status as a "German" and thus "political" general, serving under a series of less-than-outstanding superiors, such as McClerndan and Canby, as well as his own lack of political ambition, contribute to Osterhaus' low profile, not to mention an almost complete dearth of private papers. 

Yankee Warhorse not only provides an interesting look at an able, though overlooked commander, but is also valuable for its treatment of the very chaotic early months of the war in Missouri and Arkansas and for a number of interesting battle pieces.