Complex sentence: The modern law formalizing its annual observance was enacted in 1952, although earlier days of fasting and prayer had been established by the Second Continental Congress from 1775 until 1783, and by President John Adams in 1798 and 1799.
Split into simpler sentences: The modern law formalizing its annual observance was enacted in 1952. Earlier days of fasting and prayer had been established by the Second Continental Congress from 1775 until 1783, and by President John Adams in 1798 and 1799.