Brent,

I wondered if Spring River might be the name.

This sounds like a very representative example of the small engagements in Missouri and Arkansas. The Union force was little more than battalion or small regiment strength. They brought a single piece. And they broke up a similarly sized CSA force in the act of organizing/reorganizing.

Not being familiar with the engagement I assume that the Union commander vastly overestimated CSA losses. Typical was 2X or more in this sort of fight. However, if one can locate the POW records they might help verify the range.

I suspect the cannon was a 12-pounder mountain howitzer, absent any other data. They appear to have been the most common small cannon integrated into other units in this theater.