There is no record of copyright entry or deposit for “I Will Be True to Thee,” but later copies of the song have an 1862 copyright claim on page three.
I will be true to thee
1880
S.T. Gordon & Son
1873
Charles W. Harris
1866
C.M. Tremaine O. Ditson & Co.
Horace Waters O. Ditson & Co.
1870/1871
1874
1862-1899 1862/1899
[C. Sheard
1862
1864
1872/1873
1867