Answer:
Lincoln shows that the Union was destined to fail because the country chose to allow slavery while claiming national values of freedom and liberty.
Step-by-step explanation:
In the passage from Lincon's speech shown in the question above, we can see that he places the blame for all the damage and disadvantages that the war brought to the country, in the government itself.
He claims that the government was contradictory in what it swore to defend, freedom. When the government established slavery as normal and acceptable, it renounced the freedom that it so advocated and that renunciation was the main cause of the war.
In short, Lincoln shows that the Union was destined to fail because the country chose to allow slavery by claiming national values of freedom and freedom.