Taking the risk of opening another can of worms...
ARPANET wasn't the first large scale data network.  I believe SITA HLN
was world-wide by 1969.  However it was a mix of switching technologies
 from fully automated to manual depending on what part
of the world you  
were in.  Frankfurt was the first SITA node to transition to fully
automatic data routing in 1966.
And ARPANET wasn't the largest data network when TCP/IP was formalized
in the early 80s.  We only recognize it as the 'Internet' because of
it's lineage.
-Alan
On 2019-11-24 17:07, Murray McCullough via cctalk wrote:
  The first Internet message was sent 60 yrs. ago on
Nov. 21 between SRI
 and
 UCLA. It was one-to-many, or more accurate one-to-one, but the world
 today
 is many-to-many though cctalk runs through a moderator. The Internet
 democratizes and gives a certain freedom to us all but it can lead to
 mis-information  from "one" or mis-interpretation by the "many".
 Computerization of society as seen through cctalk tells this story well
 mainly through the hardware side.
 Happy computing.
 Murray  ?