Guru Hargobind Sahib Ji wore two swords at his installation in 1606, naming them miri and piri, temporal authority and spiritual authority, and built the Akal Takht facing the Harmandir.
The physical arrangement states the doctrine. The Harmandir is lower than the ground and open on four sides; the Akal Takht is raised and faces it. A Sikh moves between the two.
The principle is that spiritual and temporal authority are not separable and that a religious community has an obligation in the world, including an obligation to resist.
Its practical consequence has been that Sikh religious institutions have always been political, which is why the SGPC is contested at elections and why hukamnamas from the Akal Takht have political effect.
Every argument in Sikh public life about whether religion should be in politics is an argument about how to read two swords worn in 1606, and both sides quote them.
The two swords were taken up by Guru Hargobind Sahib Ji at his succession in 1606, immediately after the death of Guru Arjan Dev Ji in Mughal custody. The order of those events is the argument.
Every later Sikh political claim rests on it: the Khalsa's territorial rule, the Akali assertion that the gurdwaras were a political question, and the Anandpur Sahib Resolution.
The counter-reading, that the two are distinguished precisely so that neither absorbs the other, has been made throughout by those who resist clerical control of politics. The doctrine has never settled the question it is used to settle.