Final answer:
Guru Har Gobind significantly influenced Sikhism by introducing the concept of 'Miri and Piri', which merged spiritual and temporal authority, leading to the militarization of Sikhs in response to Mughal persecution. He fortified Sikh towns, created a militia, and set the precedent for Sikhs to be both saints and soldiers.
Step-by-step explanation:
Har Gobind, the sixth Sikh Guru, had a significant impact on the character of Sikhism that extended beyond its spiritual aspects. He was instrumental in the militarization of the Sikh community; a transformation driven by the need to resist persecution, particularly under Mughal rule. Guru Har Gobind donned two swords, representing the dual concept of 'Miri and Piri', which signifies the combination of temporal (political/martial) and spiritual authority. This ideology was a response to the execution of his father, Guru Arjan, by Mughal emperor Jahangir.
Under Guru Har Gobind, Sikhs fortified their towns, formed a standing militia, and engaged in armed battles with the Mughals. Thus, Guru Har Gobind established the roots of Sikhism as a faith that would not only focus on personal and spiritual growth but also on the defense of righteousness and justice, encouraging Sikhs to be both saints and soldiers. Moreover, the action of creating a warrior community had lasting implications for the Sikhs as they navigated a turbulent period in their history, facing oppressions and playing a crucial role in regional politics. This martial tradition was carried forward by succeeding Gurus and became a hallmark of Sikh identity.