Complex sentence: By then it was apparent that the main Dutch force was attacking from the east and the bombardment on São Francisco was just a feint, so the commander of the São Thiago garrison sent off 50 men under Captain João Soares Vivas to aid the inland defense.
Split into simpler sentences: By then it had become apparent that the main Dutch force was attacking from the east and that the bombardment on São Francisco was just a feint. The commander of the São Thiago garrison therefore sent 50 men under Captain João Soares Vivas to aid the inland defense.