Duty first.....

नृशंसमनृशंसंवा प्रजारक्षणकारणात्।

पातकम् वा सदोषं वा कर्तव्यं रक्षतां सदा॥ 

राज्यभारनियुक्तानामेष धर्मः सनातनः। २५--१८

श्रीमद्वाल्मीकिरामायणे बालकाण्डे 

nṛśaṁsamanṛśaṁsam vā prajārakṣaṇakāraṇāt|

pātakam vā sadoṣam vā kartavyam rakṣatām sadā||

rājyabhāraniyuktānāmeṣa dharmaḥ sanātanaḥ| 25--18 

śrīmadvālmīkirāmāyaṇe bālakāṇḍe 

Ostensibly to protect a Yajna or fire sacrifice being conducted by him, sage Visvaamitra takes the boys Rama and Lakshmana with him to the forest.. 

Various stories and anecdotes are explained to the boys during their sojourn with the sage.. 

In the first lap of their journey into the forest by foot, they enter the forest called Taatakaavanam, where the fierce demoness Tataka was residing.. She was a nightmare to all living beings in the forest as also the inhabitants of the human settlements around the forest.. 

She was extremely cruel and killed and destroyed others without any scruples, but she had terrible strength which could not be matched by others around in any sort of combat.. 

The sage, in the company of Princes Rama and Lakshmana comes face to face with the demoness, and, as usual the massive lady starts her threats and abuses, now directed at the sage and the princes.. 

Vishvamitra without any hesitation instructs Rama to send an arrow at her and finish her off.. 

Rama knows that the task is very easy for him.. But He is in a dilemma because He was facing a woman in combat, and killing a woman was abhorrent for a warrior.. 

Then Visvamitra reminds Rama of His duties as an enforcer of law, a representative of the King who is duty bound to protect his own subject.. 

The above sloka in Valmikiramayanam, Balakandam, comes as an advise and strict instruction by sage Visvamitra to Rama 

" When a duty is cast on a King or his representative in the interest of protection of the Subjects of the Kingdom, such person is bound to act irrespective of the fact whether that act is virtuous or contemptible, whether it is a grave sin in public eye, or whether it is likely to attract a lot of criticism. 

This is the eternal Dharma or rule of conduct for a king who is interested and dutybound to protect the subjects dependent on him' 

Rama followed the instruction and slayed Tatakaa.. and the rest in legend. 

Vishvamitra's advice would sound Machiavellian, but when the defence and protection of the State and the citizens are concerned, all other scruples should be relegated to the background.. 

I think this happens in realpolitik ..irrespective of political systems, and time-frames in history..