(1). When Amir al-mu'minin put Ziyad ibn an-Nadr al-Harithi and Shurayh ibn Hani al-Harithi in command of contingents of eight thousand and four thousand strong at the camp of an-Nukhaylah and ordered them to advance towards Syria (ash-Sham) some dispute arose between them about their ranks of which they apprised Amir al-mu'minin and wrote letters of complaints about each other. In reply Amir al-mu'minin wrote

[ 11 ] ومن وصية له عليه السلام

وصّى بها جيشاً بعثه إلى العدو

فَإِذَا نَزَلْتُمْ بِعَدُوًّ أَوْ نَزَلَ بِكُمْ، فَلْيَكُنْ مُعَسْكَرُكُمْ فِي قُبُلِ (1) الْأَشْرَافِ (2) ، أَوْسِفَاحِ (3) الْجِبَالِ، أَوْ أثْنَاءِ (4) الْأَنْهَارِ، كَيْما يَكُونَ لَكُمْ رِدْءاً (5) ، وَدُونَكُمْ مَرَدّاً (6) ، وَلْتَكُنْ مُقَاتَلَتُكُمْ مِنْ وَجْهٍ وَاحِدٍ أَو اثْنَيْنِ اجْعَلُوا لَكُمْ رُقَبَاءَ فِي صَيَاصِي الْجِبَالِ، (7) وَمَنَاكِبِ (8) الْهِضَابِ (9) ، لِئَلاَّ يَأْتِيَكُمُ الْعَدُوُّ مِنْ مَكَانِ مَخَافَة أَوْ أَمْن. وَاعْلَمُوا أَنَّ مُقَدِّمَةَ الْقَومِ عُيُونُهُمْ، وَعُيُونَ الْمُقَدِّمَةِ طَلاَئِعُهُمْ. وَإِيَّاكُمْ وَالتَّفَرُّقَ، فَإِذَا نَزَلْتُمْ فَانْزِلُوا جَمِيعاً، وَإِذَا اَرْتحَلْتُمْ فَارْتَحِلُوا جَمِيعاً، وَإِذَا غَشِيكُمُ اللَّيْلُ فَاجْعَلُوا الرِّمَاحَ كِفَّةً (10) ، وَلاَ تَذُوقُوا النَّوْمَ إِلاَّ غِرَاراً (11) أَوْ مَضْمَضَةً (12) .

to them that when they marched jointly the command of the whole force would be with Ziyad ibn an-Nadr al-Harithi and when they marched separately each would be in command of the force over which he had been placed. 

In this letter Amir al-mu'minin also wrote for them certain instructions.  Here as-Sayyid ar-Radi has taken down only the portion containing the instructions. These instructions are not only useful as concerns the strategies of fighting of those days but their utility and importance in bringing out the principles of fighting in these days also is undeniable. These instructions are that at the time of encounter with the enemy the forces should be encamped on the tops of mountains and turns of rivers because in this way the low areas of the rivers would serve as trenches and the peaks of mountains as the walls of the fortress and thus it would be possible to feel secure and face the enemy from the other side. Secondly that tile attack should be from one side or at the most from two sides because by distribution of the entire force on several fronts weakness would inevitably arise. Thirdly that the watchers should be put in position on the tops of high ground and the peaks of mountains so that they may give warning before the attack. Sometimes it happens that instead of attacking from the expected side the enemy attacks from a different side. Therefore if watchers are in position in high places they will detect the enemy from the cloud of dust seen from a distance.

To clarify the useful aspect of these instructions Ibn Ahi'l-Hadid has recorded (in vol.15 p.91) a historical incident that when Qahtabah (ibn Shabib at-Ta'i) encamped in a village after leaving Khurasan he and Khalid ibn Barmak went and sat on the top of a nearby hill. No sooner had they sat down than Khalid noticed flocks of deer coming running from the forest. On seeing this he said to Qahtabah "O' commander get up and announce to the army that they should at once fall in line and takeup  arms." Hearing this Qahtabah was startled and stood up but looking hither and thither said "I do not see the enemy's men anywhere." He replied "O' Amir this is not the time that should be lost in conversation. You see these deer which are proceeding towards the people leaving their abodes. This means that the army of the enemy is marching from their rear." Consequently he ordered his army to get ready. As soon as the army got ready the noise of horses' hoofs was heard and within moments the enemy was on them. Since they had prepared themselves for defence in time they defended themselves against the enemy thoroughly. Now if

Khalid had not been at such a height and had not acted with such sagacity   the enemy would have attacked them unawares and annihilated them. Fourthhly that the reconnaissance should be spread here and there so that they can be aware of the movements and intentions of the enemy and thereby foil his plans. Fifthly that when the army camps it should camp together and when it moves it should move together so that the enemy does not attack you in a state of dispersal and overpower you easily. Sixthly that at night the guard should be formed by fixing spears in a circle in the ground so that if the enemy attacks in the night it is possible to prepare for defence by taking up arms at once and if the enemy showers arrows that too can be defied. Seventhly that deep sleep should be avoided lest you remain unaware of the enemy's approach and he succeed in attacking you before you get ready.