The use of the chemical agentsi dont deny the use of such weapons in morocco, i am however incredulous as to it being a historical first, or that it was tactically useful
Spain was one of the first powers to use chemical weapons against civilian populaces in their use against the Rif rebellion. Between 1921 and 1927, the Spanish army indiscriminately used phosgene, diphosgene, chloropicrin and mustard gas (known as Iperita
as stated in wiki.