Verified Answer :

It shows that no one wants to take responsibility for starting
the war.  All had swords drawn but they
accuse each other of killing the peace. The death of the Archduke set off a
chain of events where all those involved had a hand in starting the war through
their alliances and political maneuvering.

Answer:

The death of the archduke set off a chain of events where all those involved started the war through their alliances and political maneuvering.