How did the end of feudalism aid in the creation of the sovereign states?

One aspect of a sovereign state is that the government of
that state controls all the territory within the state and holds a monopoly on the
"legitimate use of force" within the state.  That is, only the government has the right
to use armed force within the country in most circumstances.  These conditions did not
exist under feudalism.  Feudalism, therefore, had to end before states could be truly
sovereign.

In a feudal society, all sorts of lords beneath
the level of the monarch have legal control over their small territories.  They rule
those areas and have the right to use force within them.  In theory, they are
subordinate to the monarch, but that is not always how it is in practice.  Often, some
lords get to be so powerful that monarchs cannot control them and do not effectively
rule the land where those lords hold sway.

The end of
feudalism puts an end to that system.  It makes it much easier for the central
government to rule every bit of land in the country because it takes power away from
these lords who can compete with monarchs for control.  In this way, the end of
feudalism helps to allow the creation of sovereign states.