King Louis XIV of France emerged from the Franco-Dutch War

[Volcano1985]

King Louis XIV of France emerged from the Franco-Dutch War in 1678 as the most powerful monarch in Western Europe, but ----- he had expanded his
realm, the 'Sun King' remained unsatisfied.

A) just as
B) as if
C) unless
D) since
E) although

Could you explain me why the key is E?

[Soup]

Hello Volcano1985

It's used to express an unexpected resultor contrast:

• He remained unsatisfied even though he expanded his realm.

[Volcano1985]

Hello Volcano1985

It's used to express an unexpected resultor contrast:

• He remained unsatisfied even though he expanded his realm.

What is "but" to be then?

[Soup]

But is a coordinating conjunction. It joins two sentences. Although is a subordinating conjunction. It heads a dependent clause.