Coalition Wars was a 7-part series of books about the Coalition States' war that resulted in a siege on the city of Tolkeen.
It also used the subtitle Siege on Tolkeen which became the more popular moniker to refer to the series as, despite the smaller font and length.
Likely because "SOT" etc made an easier one-syllable acronym compared to the four-syllable initialism "CW".
Using SOT could cause some confusion however, since prior to the publication of Coalition Wars in the early 2000s, a 1990s story in the Rifter ALSO used that title.
That story went in different directions than Palladium ultimately chose to go.
The titles are: