De Saussure served five two-year terms in the South Carolina General Assembly in 1848–1849, 1854–1857 and 1860–1863.

[4] In August 1861, de Saussure was appointed a brigadier general in the South Carolina militia and was given command of the 4th Brigade for the remainder of the war.

[4] De Saussure commanded a force of militia and Confederate States Army troops during the siege of Charleston in 1863.

[4] In late 1864 and early 1865, de Saussure's men were sent to oppose the forces of Union Major General William T. Sherman as they marched through the Carolinas.

[4] After the war, Wilmot G. de Saussure was a prominent lawyer and was active in civic affairs in Charleston.

[10] Brother de Saussure served as Grand Sire during the term 1853–1855 – being installed in Philadelphia, Pennsylvania, and presiding in Baltimore, Maryland.

[citation needed] Wilmot Gibbes de Saussure died on February 1, 1886, in Ocala, Florida, where he had gone with the hope of restoring his deteriorated health.