The Galen border conflicts occurred between the United Federation of Planets and the Talarian Republic in the late 2350s. These skirmishes lasted three years, during which the Talarians utilized unconventional warfare methods against Starfleet.
One such battle took place on border planet Galen IV, when the Talarians attacked a Federation colony, killing everyone except Jeremiah Rossa, a human boy. Endar, a Talarian captain, adopted Rossa as his own, renaming him Jono.
Castral I was another such border planet that saw action. Endar had lost his son during a battle on Castral I, allowing him, under Talarian tradition, the right to take Rossa as his child.
The Federation and Talarians signed peace treaty at the conflicts' end. The treaty was nearly null in 2367 when Federation and Talarian interests fought over Jono, with the Federation interests wanting his return to his original family, while the Talarian interests wanted him to return to his adopted people. USS Enterprise-D captain Jean-Luc Picard made the decision to return Jono to his adopted family, avoiding warfare between the two powers. (TNG: "Suddenly Human")
- In fanon, it has often been theorized that the Galen border conflicts were related to the Federation-Cardassian War, as the sectors near Talarian space are numbered near in sequence to the sectors near Cardassian space.