Texas was annexed by the United States in 1846 and war broke out again with Mexico, Lamar joined the U.S. Army. He fought in the battle of Monterrey and helped organize a municipal government in Laredo. In his later years, Lamar traveled, wrote poetry, and spoke out in support of slavery in the South.
The article refers to third parties as gadflies because third parties often bring attention to political, social, or national issues that neither major party wants to discuss.