Introduction:
Shivaji, also known as Chhatrapati Shivaji Maharaj, was a prominent Maratha warrior and the founder of the Maratha Empire in western India during the 17th century. He is known for his military tactics, administrative reforms, and establishment of a strong naval force. In order to strengthen his army, Shivaji sought assistance from European powers to acquire cannons and ammunition.

Identification of the European power:
The European power from which Shivaji obtained cannons and ammunition was the Portuguese.

Explanation:
1. Trade relations with the Portuguese: The Portuguese were one of the earliest European powers to establish trade relations with India. They had a significant presence along the western coast of India, including Goa, which was their major trading center.

2. Portuguese artillery: The Portuguese had a well-established artillery production and trade network. They were renowned for their cannons and ammunition, which were considered superior to the indigenous weapons available in India at that time.

3. Shivaji's diplomatic relations: Shivaji was a shrewd diplomat and strategically formed alliances with various European powers to strengthen his position. He maintained friendly relations with the Portuguese and sought their support in acquiring modern weaponry.

4. Trade agreements: Shivaji negotiated trade agreements with the Portuguese, which included the procurement of cannons and ammunition. These agreements allowed Shivaji to acquire the necessary artillery for his army.

5. Benefits for the Portuguese: The Portuguese saw an opportunity to expand their influence in the region through their association with Shivaji. They also benefited economically from the trade agreements and the demand for their cannons and ammunition.

6. Impact on Shivaji's military capabilities: The acquisition of cannons and ammunition from the Portuguese significantly enhanced Shivaji's military capabilities. The modern artillery provided him with a technological advantage over his adversaries and played a crucial role in his successful military campaigns.

7. Continued relations: Shivaji's association with the Portuguese continued throughout his reign, and he maintained a cordial relationship with them despite occasional conflicts with other European powers.

Conclusion:
In conclusion, Shivaji obtained cannons and ammunition from the Portuguese, one of the prominent European powers with a significant presence in India. This association allowed Shivaji to strengthen his army and establish the Maratha Empire as a formidable force in western India. The Portuguese benefited from this trade relationship and saw an opportunity to expand their influence in the region.