Final answer:
In the 1864 Presidential election, the Democrats' slogans focused on ending the war and critiquing Lincoln's wartime policies, while the Union Party promoted their success in preserving the Union and ending slavery, reflecting themes of liberty and unity.
Step-by-step explanation:
In the 1864 Presidential election, the Democrats and the Union Party (the name adopted by the Republicans for this election to appeal to war Democrats and border states) used different slogans that reflected their platforms and goals. The Democrats, who nominated George McClellan, asserted their platform with a focus on bringing an end to the Civil War and promises to preserve the Union.
The Union Party re-nominated Abraham Lincoln and their slogans emphasized the success in preserving the Union and the end of slavery, playing upon the Northern pride in their victory and the liberation achieved through war. They used slogans that underscored their commitment to 'liberty and union', as evidenced by the Republican's reference to 'Let Us Have Peace' by Ulysses S. Grant in the subsequent 1868 election, although this specific slogan was used after the 1864 election.