Complex sentence: Given that the federal government was unwilling to fund militia not under its control, the legislature authorized Strong to borrow money to fund a major expansion of the militia, but most of the funds acquired were spent improving Boston's defenses.
Split into simpler sentences: Given that the federal government was unwilling to fund militia not under its control, the legislature authorized Strong to borrow money to fund a major expansion of the militia. Most of the funds acquired were spent improving Boston's defenses.