In 88 BCE, Lucius Cornelius Sulla (138-78 BCE) marched on Rome and entered the city's sacred inner boundary, the pomerium, bearing arms. Breaking this taboo, he sought to gain political power and control of the army of the East that had been offered to his enemy, Gaius Marius (c. 157-86 BCE). A second march occurred in 83-82 BCE when he assumed the title of dictator.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/2146/sullas-march-on-rome/.