The <em>effect</em> of the <em>figurative language</em> in this passage, apart from <em>enriching the passage</em>, is <em>illustrating more vividly the reason why those would escape</em> (the strong connection that exists between those who escape and their friends.)
Explanation:
In the given passage, the figurative language is represented by the <em>phrase</em>:
<em>the strong cords of affection that bind them</em>
This is a metaphor: the <em>strong cords</em> refer to those <em>love feelings</em> that act as <em>connection</em> between the people escaping and their friends. The <em>metaphor of cords and binding</em> talks about <em>how close these people are and how those strong ties (feelings of affection) would make them overcome fear or danger and try to escape.</em>
The purpose of Sherman's March to the Sea was to frighten Georgia's civilian population into abandoning the Confederate cause. Sherman's soldiers did not destroy any of the towns in their path, but they stole food and livestock and burned the houses and barns of people who tried to fight back.