After nearly two years in the Pentagon, Secretary of Defense Jim Mattis announced his resignation Thursday amid disagreements with President Donald Trump.

Mattis has become a US military legend throughout his 44 years of service, earning nicknames like "Mad Dog" and "Warrior Monk."

Known as a steady hand in a tumultous administration, Mattis preferred not to play politics, a quality that boosted admiration for the retired Marine general.

Secretary of Defense Jim Mattis has achieved a legendary status on par with the heroes of the US Military's past.

Stories of his achievements and sayings are told in the same way that Patton, Pershing, Marshall, and MacArthur. He is widely viewed as above politics — a man dedicated to his job and his country.

In his 44 years of service, Mattis rose through the ranks of the military to the very top. He has received numerous colorful nicknames — most notably "Mad Dog" and "Warrior Monk" — and made a number of memorable statements that will likely be quoted by service members for a long time to come.

Mattis said he would resign Thursday amid disagreements with President Donald Trump's policies. He has spent nearly two years as Trump's defense secretary.

Take a look at the life and career of the Warrior Monk.

Ben Brimelow contributed to an earlier version of this story.