This is the day when enthusiasm for an independent Sikh state reaches its zenith.
It's also the day when hundreds of thousands of people will gather in Surrey for the annual Vaisakhi parade.
Vaisakhi is the traditional harvest festival in Punjab celebrated by people of different faiths.
But it carries special significance for Sikhs because Vaisakhi also commemorates the founding of a military order called the Khalsa by Guru Gobind Singh.
The Khalsa was formed in 1699 to protect Sikhs and members of other faiths from being converted to Islam by the Moghuls, who had seized control of northern India.
In Surrey, the annual parade is organized by Surrey's Dasmesh Darbar gurdwara, whose leaders have traditionally been strong supporters of an independent Sikh homeland called Khalistan.
The Indian government, on the other hand, has been determined to preserve all of its territory ever since the country gained independence on August 15, 1947.
That's why independence movements have been crushed in the Indian states of Kashmir, Assam, and Nagaland. The desire for territorial integrity underlies the successful efforts of the first prime minister, Jawaharlal Nehru. and his first deputy prime minister, Vallabhbhai Patel, to bring principalities under the control of the central government.
One of the most serious uprisings occurred in Punjab in the early 1980s. A firebrand Sikh preacher, Jarnail Singh Bhindranwale, led a group of militants in an uprising against the Indian government. In 1984, they brought weapons into Sikhism's holiest shrine, the Golden Temple complex in Amritsar.
When the Indian Army attacked with tanks on the orders of then-prime minister Indira Ghandi, it created an uproar among the Sikh diaspora around the world, including in the Lower Mainland.
The assault on the Golden Temple led months later to the assassination of the prime minister by her Sikh bodyguards.
Nearly 3,000 Sikhs, mostly in Delhi, were killed in the ensuing retaliation promoted by members of Ghandhi's party. This further fuelled the movement for the creation of Khalistan.
To this day, the Indian government remains concerned about that. As recently as 2012, then-prime minister Manmohan Singh was urging the Conservative government to pay attention to the Khalistani separatist threat, which was centred in Surrey.
According to a Globe and Mail article, India's then-minister of state for external affairs, Preneet Kaur, told Harper that an "area of great concern" was "the revival of anti-India rhetoric in Canada".
Anti-India "rhetoric", if you can call it that, is on full display during the Surrey Vaisakhi parade. There, you'll see photos of Bhindranwale on T-shirts, posters, and even on floats travelling in a parade that also includes a large number of RCMP officers and politicians.
In the past, the Surrey Vaisakhi parade has even celebrated the assassins of Indira Ghandi and the reputed mastermind of the Air India bombings, Babbar Khalsa founder Talwinder Singh Parmar. They're viewed as martyrs among some supporters of an independent Khalistan.
This was the backdrop to Indian prime minister Narendra Modi's visit to Vancouver and Surrey on April 16.
Modi has generated a surprising amount of support among younger Indians because of his charisma and for embracing modern technologies in his political campaigns, including holographic effects to place him in numerous locations at the same time.
It's one reason why he's being referred to as a rock star.
Modi is, in fact, unleashing patriotic fervour about India among the so-called NRIs (non-resident Indians).
Modi could have come to Canada during any part of the year to discuss trade and commerce with Prime Minister Stephen Harper. So why this week?
It's easy to conclude that the date of his visit to Surrey was designed to promote an intense love of India just before the Vaisakhi parade was about to whip up support for an independent Khalistan.
In politics, timing is everything.