Military: War
From the war of independence, to the grand campaign that crush the empire down.
Following by the revolution, The kingdom defend itself from reconquest, and stop their influence completely.
As war continued, the powerful arms became more obvious, the scale become larger, and reconquest became reversed.
They won so many battles and sieges since then, bit by bit, and nothing could stopped them now. Even they took very long to do so, the old empire, where Valonian feared and hated, was eventually collapsed.