During the American Civil War, Owen served in the Ordnance Commission to supply the Union army; on March 16, 1863, he was appointed to the Freedman's Inquiry Commission. The commission was a predecessor to the Freedmen's Bureau.  In 1862 Owen wrote a series of open letters to U.S. government officials, including President Abraham Lincoln and U.S. Secretary of the Treasury Salmon P. Chase, to encourage them to support general emancipation. Owen's letter of July 23, 1862, was published in the New York Evening Post on August 8, 1862, and his letter of September 12, 1862, was published in the same newspaper on September 22, 1862. In another open letter that Owen wrote to President Lincoln on September 17, 1862, he urged the president to abolish slavery on moral grounds. Owen also believed that emancipation would weaken the Confederate forces and help the Union army win the war. On September 23, 1862, Lincoln issued a preliminary version of the Emancipation Proclamation (as he had first resolved to do in mid-July). In Emancipation is Peace, a pamphlet that Owen wrote in 1863, he confirmed his view that general emancipation was a means to end the war. In The Wrong of Slavery, the Right of Emancipation, and the Future of the African Race, a report that Owen wrote in 1864, he also suggested that the Union should provide assistance to freedmen.  Toward the end of his political career, Owen continued his effort to obtain federal voting rights for women. In 1865 he submitted an initial draft for a proposed Fourteenth Amendment to the U.S. Constitution that would not restrict voting rights to males. However, Article XIV, Section 2, in the final version of the Amendment, which became part of the U.S. Constitution in 1868, was modified to limit suffrage to males who were U.S. citizens over the age of twenty-one.

Answer this question "what were these letters about" by extracting the answer from the text above.
to encourage them to support general emancipation.