"All for our Country":
The motto has always been part of the state seal but there is no documented source of its originality.
Nevada entered the Union as a state during the Civil War and just before the presidential election of 1864. The Constitutional Convention met in Carson City on July 4, 1864, one year after the battle at Gettysburg. The Union needed another state, another supporter of President Lincoln, to prove to the Confederacy that the Union was strong. Patriotism was running high here and those assembled for the Convention felt very loyal to the Union and quite willing to do what they could to support it.
Article V, Section 15 of the Nevada Constitution states that there is to be a state seal. In the second legislative session (1866), Assemblyman A. B. Elliot of Storey County introduced Bill 26. It was read and referred to the Committee on State Library. They returned it to the Assembly for another reading. It passed there and went to the Senate.
In the Senate, AB26 was referred to the Committee on State Affairs. On February 19, 1866, Senator Lockwood reported that the Committee had AB26 under consideration, had come to a favorable conclusion thereon, and directed their chairman to report the same to the Senate, without amendment, and recommended its passage. On the third reading it passed 12-1.
The statutes of 1866 (chapter XLI) gives a complete description of the design. The last sentence reads "In an outer circle, the words, "The Great Seal of the State of Nevada," to be engraven with these words, for the motto of our State, "All for Our Country."
Unfortunately, there are no records of the committee proceedings, discussions, nor any legislature's discussion of the seal, to tell us how or why or who came up with "All for our country."