Significance - Sikh Chronicles
Prachin Panth Prakash
Sri Gur Panth Prakash commonly known as Prachin Panth Prakash written by Rattan Singh Bhangoo is considered one of the primary historical chronicles and seminal works about the origin and evolution of the Khalsa Panth, during the 18th century. The author Rattan Singh Banghu started the work in 1809 and completed it in 1841. Noted scholar Bhai Vir Singh discovered the original manuscript in 1914, editing and then published it that year.
Ratan Singh Bhangu drew upon available Sikh sources such as Janamsakhis and Gurbilases and on the oral history tradition passed down to him from his family. His paternal grandfather was the famous Sikh martyr Matab Singh and his maternal grandfather Sham Singh was the leader of the Karorasirighia Misl. Prachin Panth Prakash is one of the few historical Sikh source of information that we have about the establishment of early Sikh rule in the Punjab during the time of Banda Singh Bahadur.
The references to Nishan Sahibs in Prachin Panth Prakash  reveal that they were an important symbol of the struggle for religious freedom against the oppression of the Mughal Empire during the 18th century.
Episode 23, Now I Narrate the Episode at Muktsar Sahib
The Majhail Khalsas immediately took positions at this spot,
And planted their Khalsa standards on the ground.
They declared war with the beat of the Khalsa drum,
And fired shots in the air from their loaded muskets. (19)
Episode 27, The Episode About Banda Bahadur
It was marked by beating of drums and unfurling of Khalsa flags,
And a loud recitation of Gurbani without any kind of fear.
The Guru’s Singhs were heard reciting “Chandi Chritar” and “Chandi di Var”,
As well as the recitation of Guru’s compostion, “Akal Ustat”. (2)
Guru’s Khalsa’s standards shone like a brilliantly shining sun,
Likewise shone the sparkling majestic waving hand fans.
The canopy over Guru’s head sheltered his face like a dark cloud,
Under a vast outstretched tent like a thick huge cloud. (9)
Episode 43, The Episode of Malerkotla
Banda Singh got (the Khalsa) standards planted at Panipat,
So that no Mughal force could dare to cross the Khalsa territory.
Even as some burglar tried to pull out the poles of Khalsa flags,
These went still deeper than their earlier positions into the earth. (15)
If someone tried to cut the supporting ropes with a sharp weapon,
His own arms would get amputated with the first contact,
No security guards were deputed to guard these Khalsa standards,
Since a Muslim intruder’s body would get instantly burnt in its proximity. (16)
Episode 44, The Episode About Doaba Region
The Khalsa’s standards were hoisted,
And all the Mughal flags were thrown down
The Khalsa standards kept fluttering without any support,
Since no Muslim dared to come near these flags.
The Khalsa forces set up a military cantonment at Amritsar,
Since no invader could now uproot their establishment from this site. (5)
Bahi Khan Singh Nabha
According to popular Sikh tradition the first Nishan Sahib was erected by the 6th Sikh Guru, Guru Hargobind at Amritsar on the newly constructed Akal Bunga (now called the Akal Takht) upon it’s completion in 1608. This account states that no flags or banners were used by prior Gurus. The account mentions that the flag erected by Guru Hargobind was saffron and the top of the flagpole had a pointed spear like khanda. 
The source of this account is the Sikh scholar Bhai Khan Singh Nabha and appears in Gurmat Martand (pg 616) first published in 1938 (SGPC version 1962) with additional information in Gur Shabad Ratnakar Mahan Kosh (see Jhanda Sahib) first published in 1930. Both written works are 20th century works, Bhai Khan Singh did not provide any reference or attribute any earlier source for this account.
1. Sri Gur Panth Prakash: Rattan Singh Bhangoo (Volume 1), Translated by Kulwant Singh, Institute of Sikh Studies, 2006