historyof
sanatanhindusikh
shastarvidiya

Akali Baba Buddha dispensed this very same martial knowledge he had received from Akali Guru Nanak Dev to the soldiers of the Akal Bunga, the 'Akali'.

A text of the time states:

“The reason as to why the name of this group is 'Akali' is that adjacent to the building associated with Guru Ram Das and Guru Arjan is Akal Bunga, 'The Place of Khuda' (Supreme Being)], which is associated with Guru Hargobind. The Akalis, or 'Khuda's men', as a mark of honour, are associated with this Bunga. The dress of this group was endorsed to be black in observance of mourning to mark Guru Arjan Dev's bereavement. Subsequently, this roaming community took on weapons of steel and demonstrated fearlessness at the time of a mighty assault.”
('Ibratnamah', Mufti 'Ali ud-Din (1854), ed. Muhammad Baqir, 2 vols. Lahore (1961), 1:Pa. 364–366)

Ali ud-Din's work (completed on 13 September 1854) supports the Akali Nihang oral tradition that the Akalis came about with the Akal Takht. Later, Bhai Vir Singh also endorsed this belief:

“It is believed that from the times of the sixth Sat Guru to the tenth Sat Guru, the Akal Bunga's Akalis worked directly only under their command.”
('Satwant Kaur', Bhai Vir Singh, New Delhi: Bhai Vir Singh Sahit Sadan [1992], Pa 229)

The Akalis, also known as the 'Akaal Sena' would later be known as the 'Akali Nihang Singh Khalsa' - the beloved soldiers of the Guru.