Pendleton was as a private in the Confederate Army, joining after the beginning of the Civil War and saw action with the Nineteenth Texas Cavalry[3] in the Trans-Mississippi Department.

In an effort to regain his strength through work, Pendleton accepted a job as a traveling salesman for a Dallas implement company.

[2] Pendleton was selected as state representative of the Fifty-sixth District, which included Bell County, and retained office for the Eighteenth, Nineteenth, and Twentieth legislatures; he served as Speaker of the House in 1887–1889.

In 1892 he successfully sought election to Congress from the state's seventh district, which included Bell, Falls, McLennan, Freestone, Limestone, Milam, Brazos, and Robertson counties.

[2] He also remained active in Democratic politics during his later years, serving as a chairman pro tem of the state convention in 1902 and holding a seat on the committee on platform and resolutions in 1904.

After the election of Woodrow Wilson to the presidency in 1912, Pendleton was to be appointed Postmaster of Temple, a post no doubt intended as a reward for his long service to the Democratic party.