Maria Tomasa Guerra Cañamar was born circa 1780, the daughter of Juan Manuel Guerra Cañamar and Maria Isabel Treviño.
In 1782, she lived in Mier. The church census recorded that she was a young child, española, and 2 years old. Her household included 6 people:
Juan Manuel Guerra Cañamar, español, married, age 40.
Isabel Maria Treviño, española, married, age 26.
Jose Francisco Guerra Cañamar, español, a young child, age 6.
Antonio Matias Guerra Cañamar, español, a young child, age 5.
Maria Tomasa Guerra Cañamar, española, a young child, age 2.
Jose Ysidoro Guerra Cañamar, español, a young child, age 1.