If you say that something such as someones death, suffering, or effort was in vain, you mean that it was useless because it did not achieve anything. He wants the world to know his son did not die in vain.
Secondly, what does highly resolve mean? resolve. To resolve is to settle or make a decision about something — often formal. A colleges board of directors might resolve to recruit more minority students. As a noun, resolve refers to a strong determination to do something.
Beside this, what does it mean if someone dies in vain?
Dying in vain refers to someone who sacrifices themselves for a cause, and their sacrifice ends up not helping. For example, a person who sacrifices themselves to save a child, but then the child dies anyway, is said to have died in vain.
What does Lincoln mean when he says the world will little note nor long remember what we say here but it can never forget what they did here?
The world will little note, nor long remember what we say here, but it can never forget what they did here. It is for us the living, rather, to be dedicated here to the unfinished work for which they who fought here have thus far so nobly advanced.