He is described as "a gallant, hot-headed bachelor, from Tyrone County, Ireland." He was something of a beau in society, and was the subject of some satirical articles which, in a spirit of fun, Miss Mary Todd (afterwards Mrs.Lincoln) had written and published in a local journal.
Shields was furious, and, demanding the name of the writer, Lincoln sent him word that he would assume full responsibility in the matter.

A challenge to a duel followed, which Lincoln accepted and named broadswords as the weapons.

General Linder states that Lincoln said to him that he did not want to kill Shields, and felt sure he could disarm him if they fought with broadswords, while he felt sure Shields would kill him if pistols were the weapons.

It seems that Lincoln actually took lessons in broadsword exercise from a Major Duncan; and at the appointed time all parties proceeded to the chosen field, near Alton.
But friends appeared on the scene while the preliminaries were being arranged, and succeeded in effecting a reconciliation.

Major Lucas, of Springfield, who was on the field, stated that he "had no doubt Lincoln meant to fight.