John Riley of K
Company, 5th
Infantry 21
deserted his
American post and
joined the Mexican
ranks on April 12,
1846 22
prior to the US
declaring war on
Mexico. It is
important to note
that Riley defected
the American ranks
prior to the actual
declaration of war,
thus it was peace
time when he
abandoned the US
Army. He is
generally credited
with organizing the
Irish Battalion.
Part of the
confusion, over
whether Riley
organized the
battalion is caused
by the different
spellings of his
name found in
official government
records. John Riley,
himself signed his
name as Riley, other
times as Riely,
Reilly, or O’Riley
in his
correspondence to
others. Mexican
government records
list him as Juan
Reyle, Reley, Reely
or Reily. His
enlistment record
for the U.S. Army
lists him as Reilly.
23
On September 2,
1845, Riley enlisted
for a five-year term
at Fort Mackinac. He
left for the Texas
border two days
later. During the
last three weeks in
March of 1846,
Riley, under
Taylor’s Army, setup
camp in Texas, just
across the river
from Matamoros. On
April 12, 1846,
Riley obtained a
pass from Captain
Merrill to attend a
Catholic Mass,
deserted and joined
the Mexican Army.
24
According to the
records of the
period, Sergeant
John Riley’s ability
was such that he was
in line for a
lieutenant’s
commission although
rising through the
ranks during this
period was difficult
at best. 25
This
discredits some of
the misinformation
put out by some
publications of the
period that
attempted to suggest
that Riley was a
malcontent soldier.
Although, some
historians have
argued that Riley
did not actually
form the San
Patricio Battalion,
the plaque in Mexico
City commemorating
their contribution
to the war gives
credit to Riley for
the formation of the
battalion. 26
By most general
accounts, The
San Patricios
fought bravely
throughout the war.
The Battle of Buena
Vista and Churubusco
is where the
battalion left its
most notable war
marks.
