This is a Spanish-American War era soldier. The "3" stands for the number of the regiment and of course the "TENN" is for the state of Tennessee so this would be the 3rd Tennessee Infantry.

During the WBTS the symbol of infantry was a trumpet. The crossed rifles were not used as a symbol of infantry until November 19, 1875.

I hope this helps.

Respectfully,

Gerald D. Hodge, Jr.
Lieutenant Colonel, U.S. Army