Timotheus is the name given in the 1 Maccabees

1 Maccabees

The First book of Maccabees is a book written in Hebrew by a Jewish author after the restoration of an independent Jewish kingdom, about the latter part of the 2nd century BC. The original Hebrew is lost and the most important surviving version is the Greek translation contained in the Septuagint...

 for an Ammonite general of the mid 2nd century BCE. He was defeated by Judas Maccabeus

Judas Maccabeus

Judah Maccabee was a Kohen and a son of the Jewish priest Mattathias...

 at Dathema

Dathema

Dathema or Diathema was the name of a fortress in Gilead to which the Jews fled when hard pressed by Timotheus of Ammon. There they shut themselves in, prepared for a siege, and sent to Judas Maccabeus for aid...

 in Gilead

Gilead

In the Bible "Gilead" means hill of testimony or mound of witness, , a mountainous region east of the Jordan River, situated in the Hashemite Kingdom of Jordan. It is also referred to by the Aramaic name Yegar-Sahadutha, which carries the same meaning as the Hebrew . From its mountainous character...

.

Some scholars maintain that Ammon had ceased to exist as a distinct nation by this time, and that the designation of Ammonite as applied to Timotheus is geographic rather than ethnic; the account of Justin Martyr

Justin Martyr

Justin Martyr, also known as just Saint Justin , was an early Christian apologist. Most of his works are lost, but two apologies and a dialogue survive. He is considered a saint by the Roman Catholic Church and the Eastern Orthodox Church....

(who maintained that Ammonites were numerous in his period) call this hypothesis into question.