As early as Xenophon, ingratitude has seen as a cause of sedition, and during the middle ages the social and political context of feudalism strengthened this link. Xenophon wrote, “And they [the Persians] bring one another to trial also charged with an offense for which people hate one another most but go to law least, namely, that of ingratitude; and if they know that any one is able to return a favour and fails to do so, they punish him also severely. For they think that the ungrateful are likely to be most negligent of their duty towards the gods, their parents, their country, and their friends; for it seems that shamelessness goes hand in hand with ingratitude; and it is that, we know, which leads the way to every moral wrong” (Xenophon, Cyropaedia, 1.2.7 [Loeb Classical Library; Walter Miller, trans.; Cambridge: Harvard University Press, 1914]). 

Seneca agrees: “There always will be homicides, tyrants, thieves, adulterers, ravishers, sacrilegious, traitors: worse than all these is the ungrateful man, except we consider that all these crimes flow from ingratitude, without which hardly any great wickedness has ever grown to full stature” (De Beneficiis, 1.9).

For Elizabethans, it was a truism that the ungrateful citizen who refused to acknowledge the direct beneficence of his prince and or the various less tangible benefits that arise from stable political order would be a potential traitor. Shakespeare dramatized the ingratitude of treason in a number of plays. 

The theme is established early in Julius Caesar, when the patrician Marullus chides the churning populace of Rome for their fickleness toward Pompey. Not long ago, he claims, they were celebrating Pompey’s triumphal return to the capital, but now they celebrate with equal enthusiasm the advent of Julius Caesar, who comes riding over Pompey’s blood. He warns that the gods will not tolerate it, and characterizes their fault as “ingratitude” toward the service and memory of Pompey: “Run to your houses, fall upon your knees,/ Pray to the gods to intermit the plague/ That needs must light on this ingratitude” (1.1.52-54). Their forgetful ingratitude deprives them of humanity: “You blocks, you stones, you worse than senseless things!” (1.1.35).

Ultimately, the plague that ingratitude unleashes on Rome is the plague of civil war. Though the populace’s ingratitude provides important background to the war, the central ingratitude is shown by Caesar’s friends and associates, notably Brutus. By Mark Antony’s lights, ingratitude killed Caesar, the “unkindest” cut being that of Brutus. As he unwraps Caesar’s body to reveal the wounds that Caesar had in service to Rome, he invites Rome to

See what a rent the envious Casca made:

Through this the well-beloved Brutus stabb’d;

And as he pluck’d his cursed steel away,

Mark how the blood of Caesar follow’d it,

As rushing out of doors, to be resolved

If Brutus so unkindly knock’d, or no;

For Brutus, as you know, was Caesar’s angel:

Judge, O you gods, how dearly Caesar loved him!

This was the most unkindest cut of all;

For when the noble Caesar saw him stab,

Ingratitude, more strong than traitors’ arms,

Quite vanquish’d him: then burst his mighty heart;

And, in his mantle muffling up his face,

Even at the base of Pompey’s statue,

Which all the while ran blood, great Caesar fell.

O, what a fall was there, my countrymen!

Then I, and you, and all of us fell down,

Whilst bloody treason flourish’d over us (3.2.172-189).

Antony describes a sequence: Brutus’s ingratitude, along with Casca’s envy, led them to become traitors in attacking Caesar; but Caesar’s fall is the fall of Rome itself. Caesar was “marred . . . with traitors” (3.2.194), but Rome herself is now under the dominion of treason (3.2.189). Significantly, Antony responds to this ingratitude with vengeance, as Caesar’s spirit, released by the killing of his body, rages over the Roman world until the traitors are dead. 

From Brutus’ perspective, his participation in the conspiracy was not the product of ingratitude but perhaps instead of a contest of gratitudes – his political debt to Republic Rome finally winning out over his personal debt to Caesar. Brutus’ tragedy thus arises from a conflict of obligations from which there is no obvious exit. (Thanks to Doug Wilson for this point.)

Ingratitude has similar effects in Titus Andonichus, where the theme again arises in the opening scene. Titus has rendered faithful service to Rome, and has supported Saturninus in his contest with his brother for the imperial throne. Saturninus thanks Titus by offering to raise his daughter, Lavinia, to the throne of empress (1.1.237-246), vowing to remember Titus’ service on pain of losing the fealty of Rome (1.1.256-260). When Lavinia is swept away by her lover, Bassianus, and Titus kills his son Mutius to return her to Saturninus, the emperor suddenly renounces his professed obligations toward the Andronici: “The emperor needs her not,/ Not her, nor thee, nor any of thy stock” (1.1.302-303), a dismissal that Titus characterizes as “monstrous” (1.1.311).

Ingratitude is prominent in another narrative thread as well. Tamora, the Gothic Queen now made Empress, is the first to speak of gratitude explicitly, as she seeks to convince her new husband to overlook Titus’ wrongs, for the moment:

Dissemble all your griefs and discontents:

You are but newly planted in your throne;

Lest, then, the people, and patricians too,

Upon a just survey, take Titus’ part,

And so supplant you for ingratitude,

Which Rome reputes to be a heinous sin,

Yield at entreats; and then let me alone:

I’ll find a day to massacre them all

And raze their faction and their family,

The cruel father and his traitorous sons,

To whom I sued for my dear son’s life,

And make them know what ‘tis to let a queen

Kneel in the streets and beg for grace in vain (1.1.446-461).

If the emperor does not time his vengeance against Titus wisely, he could provoke the ingratitude of all Rome, which would rise up in revolt. As in Julius Caesar, ingratitude is immediately linked with treason.

In Antony and Cleopatra, Enobarbus is the chief traitor, albeit a reluctant and suicidally penitent traitor. He is the Judas who leaves his master during his last supper and makes bargains with his master’s enemies. What is revealing here is that Enobarbus’s treachery is seen as treachery toward Antony specifically, and not as treachery toward Rome. Though ingratitude still leads to treason, in the imperial system, loyalty and gratitude are focused on the emperor and his largess, rather than on the city of Rome herself. 

Cantor (Shakespeare's Rome, 43-45), writes “Because in the Empire a commander generally gets credit for his subordinates’ accomplishments, the advantage is with those already in power, and the tem ptation for a commander to rest on his laurels is much greater than it is in the Republic. At the same time, for men trying to make their fortunes in the world, the inducement to perform heroic and glorious deeds for Rome is much less. . . . Preferment in the Empire is achieved through maintaining the good graces of one's commander, whatever the cost to Rome as a whole. The Republic seeks to establish a harmony between the interest of the individual and the interest of Rome, which in turn creates salutary competition for honors among subordinates and commanders.” 

Thus, there is a harmony between the interests of subordinates and commanders, with the result that interest of individual and Rome no longer coincide: “The Empire actually discourages public spiritedness by failing to provide legitimate paths for advancement to the top of the Imperial hierarchy. In the Empire there is room fro only one man at the top at a time, as the course of action in Antony and Cleopatra amply demonstrates, and unlike the Republican consul, the Emperor does not quietly step down from office after a year’s term.”

From the perspective of the Andronici, they are the ones defending Rome from tyrants, whose tyranny is of a piece with ungrateful treason. As Titus and his brother Marcus prepare to shoot arrows into the sky with messages for the gods, Marcus encourages the members of his clan to “join with the Goths, and with revengeful war/ Take wreak on Rome for his ingratitude,/ And vengeance on the traitor Saturnine” (4.3.33-35). While Saturnine and Tamora plot revenge against the “ingrateful traitors” among the Andronici, Titus’ clan seeks revenge against the traitor Saturnine, in order to avenge themselves for Rome’s ingratitude. In their ingratitude, Rome has forgotten the services done by the Andronici, and has instead chosen to follow Saturninus. Tyranny and treachery are identified here, and both are arising from ingratitude.

Ingratitude can thus issue in tyranny as well as in treason, and in this Shakespeare is reflecting Elizabethan common sense. Residually feudal in their political opinions, the Elizabethans believed that rulers and lords had obligations toward their vassals and subjects, such that subjects and administrators, and soldiers in particular, had a right to receive benefits from rulers, who depend on them for military success and orderly political life.