23rd June 2026

Explanation – It is located in Nabha city within the Patiala district of Punjab. It served as the royal residence and administrative centre of the Nabha princely state under the Phulkian dynasty.

• Constructed and expanded over more than 150 years, notable rulers like Maharaja Hira Singh (1843–1911) contributed to its grandeur with decorative frescoes, intricate carvings, and spacious courtyards.
• The fort played a significant role during the Anglo-Sikh Wars, with Nabha aligned with the British, which secured its sovereignty under colonial rule.

Architecture: The fort features traditional Indian military architecture with thick walls, bastions, and large gates designed for defence, alongside palatial residences, gardens, and audience halls showcasing a blend of Mughal, Rajput, and Sikh architectural styles. The fort also consists of painted chambers, gilding and mirror work, coloured glass and decorative fanlights, wood carvings, decorative plasterwork, stone door frames, and stone jaalis.

• Rediscovered artifacts include rare wall paintings depicting Maharaja Ranjit Singh's army and a unique cooling system in the basement known as the Sard Khana.

Explanation – It is a Chinese solid-fuelled medium-range hypersonic ballistic missile. It was officially unveiled in 2019. Its NATO code name is CSS-22.

Features:

• It is said to have a range of 1,800 km to 2,500 km.
• It is mounted on a mobile launcher.
• It carries a hypersonic glide vehicle DF-ZF (HGV — Hypersonic Glide Vehicle).

Its operation is as follows:

• The missile is launched outside the atmosphere like a classic ballistic missile.
• At a certain altitude, the DF-ZF warhead separates.
• The warhead re-enters the atmosphere, but instead of descending in a straight line like ballistic missiles, it "glides" in the atmosphere with its fins.
• While gliding, it changes direction and manoeuvres.
• Its speed is approximately Mach 5–10.
• This flight profile allows the vehicle to remain below radar detection for longer durations than a ballistic missile covering the same distance.

Explanation – Agray is the smallest (77 m, 900 tonnes) but most specialised of the three. It is an Anti-Submarine Warfare Shallow Water Craft (ASW SWC) of the Arnala-class.

• Its weapons: Lightweight torpedoes, indigenous anti-submarine rocket launchers, and sonar systems.
• Its role is to detect and destroy submarines in littoral waters — shallow coastal zones near ports, naval bases, and sea approaches.
• Coastal waters are especially tricky for sub-detection because fishing boats, merchant vessels, and seabed clutter create a noisy, cluttered acoustic environment. That is precisely where Agray operates.

Explanation – Sanshodhak is a Survey Vessel — Large (SVL). Its job is to measure and map the sea: water depth, seabed features, navigational routes, port approach channels, and oceanographic data.

• It is equipped with autonomous underwater vehicles (AUVs), remotely operated vehicles (ROVs), and multi-beam echo sounders.
• It is the last ship of the Sandhayak-class SVLs (contract signed October 2018).
• The other three are INS Sandhayak (Feb 2024), INS Nirdeshak (Dec 2024), and INS Ikshak (Nov 2025).

Why it matters: Submarines and warships don't operate in empty water. Knowing the underwater terrain — depths, currents, seabed clutter — is essential for safe navigation, submarine route planning, port management, disaster relief, and coastal development.

Explanation – Dunagiri is a stealth guided-missile frigate under Project 17A. It is the largest of the three (149 m, 6,670 tonnes). 'Stealth' here means reduced radar and sensor visibility — not complete invisibility.

Key Weapons and Systems:

• BrahMos surface-to-surface missiles
• Medium-Range Surface-to-Air Missile (MRSAM) system
• MFSTAR radar, sonar, electronic warfare systems, and anti-submarine weapons
• Its role is blue-water operations — fighting far out at sea against both conventional and non-conventional threats.
• Sister ships in Project 17A include INS Nigiri, Himgiri, Taragiri, Udaygiri, and Vindhyagiri.