Confirming grammar about verb potential form


> 異三郎の動かせる勢力の全てを島に投下

動かせる is a verb in potential form

I heard that when の particle meets a verb it usually means its a relative
clause but I'm quite sure this is not the case for this sentence

So is it correct if I consider 動かせる is more of an adjective than a verb (so it
means more like force that can be moved)

So that the whole sentence would roughly translate into: All of Isaburo's
forces that can be moved is invest on the island




Japanese potential forms are a bit tricky, but the following three sentences
are all correct:

  * 異三郎は勢力を動かせる。  
Izaburo can move the force.

  * 勢力は(異三郎によって)動かせる。  
The force is movable (by Izaburo).

  * 異三郎には勢力が動かせる。  
To Izaburo, the force is movable.

These are chosen depending on the topic of the sentence. English speakers may
find the first 動かせる is verb-like ("can move") and the other two are adjective-
like ("movable"). See also: [The difference between が and を with the potential
form of a verb](https://japanese.stackexchange.com/q/609/5010) and [Use of に
in 「私には本物の若殿様がわかります」](https://japanese.stackexchange.com/q/24955/5010)

Anyway, the sentence in question can be constructed straightforwardly from the
first bullet above.

  * 異三郎は勢力を動かせる。  
Izaburo can move the force.

  * 異三郎が動かせる勢力 (pull out 勢力 and change wa to ga)  
the force Izaburo can move

  * 異三郎 **の** 動かせる勢力 ([ga-no conversion](https://japanese.stackexchange.com/q/12825/5010))  
the force Izaburo can move

So 異三郎の動かせる is a relative clause, and this の is a subject marker that can be
used inside relative clauses. If you are familiar with ga-no conversion, this
grammar should be simplest to English speakers. Compare the following:

  * 異三郎の動かす勢力  
the force Izaburo moves

  * 異三郎の動かせる勢力  
the force Izaburo can move

