This is a flag of...
The flag was designed in 1894 to represent the province of Biscay and later proposed as the flag of the whole Basque Country. The red ground symbolizes the Biscayan people; the green saltire might represent the Oak of Guernica, a symbol of the old laws of Biscay, or Fueros; and over them, the white cross, God's symbol of Basque Catholic devotion.