the most important job for the incident commander

the most important job for the incident commander is to maintain
communications with the dispatcher

because

if the incident commander gives a string of updates to the dispatcher
.... and the dispatcher loses contact with the incident commander ...
the dispatcher can make a reasonable guess as to what further
resources are needed at the scene

the second most important job for the incident commander is the
ordering of additional resources and/or ordering a retreat and/or
ordering an evacuation of the public

the third most important job for the incident commander is the setting
of objectives and / or the delegation of various sectors / functions
to sub commanders