Deval Tower was originally spelled DeVal, and it was short for Des Plaines Valley...not sure why that was originally chosen. The original line there was the C&NW to Janesville, Fon du Lac, and Green Bay (oldest predecessor was Anthony & Fon du Lac), but IIRC was originally called the Illinois & Wisconsin. This was the first Chicago-Green Bay railroad, and its circuitous route was because it built outward from the vicinity of Janesville. Later, the line extended outward to the Twin Cities. A book I have at home indicates the original grading was done by Socrates Rand, for whom Rand Road is also named. Until 1910-11, the C&NW line was THE route from Chicago to the Twin Cities, but then the New Line (Proviso-Milwaukee, paralleling the Kenosha sub) and the Adams Cutoff (Milwaukee-Wyeville) was constructed--this is also when the current CPT was constructed to replace Wells St. Station (under the present Merchandise Mart). Not sure when the Soo first arrived, or if it ever had responsibility for controlling/maintaining the interlocking, but in the 1905-1910 timeframe when the New Line was built, C&NW definitely had responsibility for controlling Deval.
Until 1931 the C&NW main was triple track to Des Plaines and then double track to Harvard. The third main ended and some commuter trains tied up in the Des Plaines coach yard--still there, but now disconnected from the Harvard sub. In 1931, the third main was extended to Barrington. Somewhere I have an article describing the "new" ABS/ATS installation on this segment. Presumably, the whole line was semaphores before this 1931 conversion. Meanwhile, the Soo home signals were still semaphore blades until well into the 1990s. Inside the tower, a large pistol-grip lever machine dated to 1910, with a model board and operating simulated semaphore signals on the north wall. To the right of the operators desk (in the SE corner) was a small set of lever machines to control Seeger that were installed in 1931 (I believe they went to IRM in Union)--they were about twice the size of mailboxes with the same end profile and a cranking hand lever. Later, Norma was added to the leverman's duties, using a 1970s-vintage pushbutton control box that fit on a corner of the desk; it was relocated from Cedar Rapids, IA, after the gauntlet bridge was replaced with either switches or a double-track bridge (memory fails me). About 1994, the Seeger lever machines were replaced with a desktop computer that was powerful enough to run the whole plant, but didn't.
If the tower hadn't burned, I'm unaware of any plans existing at the time to un-man it, but I'd about guarantee it wouldn't still be manned today, fire or not.
It was a great place to visit, and it's too bad younger railfans won't know what hanging out with the leverman was like. Don't know if that tells you what you wanted, but it's all I remember off the top of my head right now.