In Macbeth, how does King Duncan's murder affect the people of Scotland?

Immediately following King Duncan's assassination, chaos ensues throughout the country as Duncan's sons flee to England and Ireland and high-ranking officials become suspicious and cautious. After Macbeth becomes King of Scotland, he rules as a bloodthirsty tyrant, who is willing to murder anyone he considers a threat to his authority. A conversation between Lennox and a Scottish Lord following Duncan's assassination provides insight into the hostile environment of Scotland under Macbeth's tyrannical reign. The Lord tells Lennox,

"Thither Macduff Is gone to pray the holy king upon his aid To wake Northumberland and warlike Siward, That by the help of these—with Him above To ratify the work—we may again Give to our tables meat, sleep to our nights, Free from our feasts and banquets bloody knives, Do faithful homage and receive free honors" (Shakespeare, 3.6.30-36).

The Lord's description of their country presents a grim picture of Scotland, where the citizens do not have enough food, cannot rest at night, and fear for their lives. Lennox responds by saying that their country is "suffering country Under a hand accursed!," which emphasizes the destructive, hostile environment in Scotland under Macbeth's reign. In act 4, scene 3, Macduff petitions Malcolm to return to Scotland in order to reclaim his rightful throne and restore their country to its former glory. Macduff also paints a depressing view of Scotland under Macbeth by telling Malcolm,

"Each new morn New widows howl, new orphans cry, new sorrows Strike heaven on the face, that it resounds As if it felt with Scotland and yelled out Like syllable of dolor" (Shakespeare, 4.3.4-8).

Overall, one can assume that Scotland has turned into a dangerous country, where citizens live in perpetual fear and suffer under Macbeth's tyranny following King Duncan's assassination.

In Macbeth, what are the conditions in Scotland after Duncan's murder and Macbeth's coronation?

After Macbeth assumes the throne, he tightens his grip on Scotland and acts to destroy opposition to his rule. Malcolm and Donalbain cannot return home until they come back with an army to defeat the tyrant. Banquo has been murdered at Macbeth's order, and his son Fleance was marked to die, as well, although he managed to escape. In an act of complete depravity, Macbeth ordered the slaughter of Macduff's entire family--wife and children--along with every person who made up Macduff's household. Even before he learned of the massacre of his family and servants, Macduff knew Macbeth for the monster he was:

Not in the legions

Of horrid hell can come a devil more damned

In evils to top Macbeth.

Living under Macbeth's tyranny, Scotland's only hope lies in Malcolm's attempts to gain the help of the English in overthrowing Macbeth. Malcolm was in England, living in the English court, trying to enlist the aid of Edward the Confessor, King of England. In discussing Malcom's efforts, Lennox expressed the importance of his succeeding:

Some holy angel

Fly to the court of England and unfold

His message ere he come, that a swift blessing

May soon return to this our suffering country

Under a hand accursed!

When Malcom does raise the English army, which unites with the Scots who have rebelled against Macbeth, Macbeth is defeated and killed in battle. Malcolm regains the throne that is rightfully his, and Scotland's nightmare ends.

How does King Duncan's murder affect Lady Macbeth?

Initially, all seems well. Lady Macbeth was the driving force behind Duncan's murder. It was she who set the whole thing in motion, cajoling her husband to get involved with the plot as well as planning everything down to the last detail. Yet ultimately, Duncan's murder proves her undoing, as it does with Macbeth himself. Once safely ensconced on the Scottish throne, Macbeth has no further use for his wife's advice and support, and so he sidelines her, carrying out a series of increasingly vicious murders without taking her into his confidence beforehand.

Ironically, Duncan's death comes to have a more serious short-term impact on Lady Macbeth than on her husband. Macbeth was always so unsure about getting rid of Duncan, yet now it's his wife who's wracked by guilt at her part in this heinous crime. Gradually, Lady Macbeth goes insane, wandering the halls of Dunsinane Castle, frantically trying to remove the imaginary stain of Duncan's indelible blood from her hands:

Out, damned spot! Out, I say!—One, two. Why, then, ’tis time to do ’t. Hell is murky!—Fie, my lord, fie! A soldier, and afeard? What need we fear who knows it, when none can call our power to account?—Yet who would have thought the old man to have had so much blood in him (act V scene i).

The question we need to ask ourselves is whether Lady Macbeth really has developed a guilty conscience over her part in Duncan's murder or whether she's been traumatized by her sudden loss of power and influence.