Graffiti was callously smeared across the Lions of the Great War memorial, which now stands 10ft high in Smethwick.
Vandals defaced the statute just days before Remembrance Sunday with the phrase 'Sepoys no more', while a black line was drawn through the words 'Great War'.
Sepoy was a term given to troops in the British Indian Army.
The graffiti has since been removed and West Midlands Police has confirmed it is investigating the graffiti as racially aggravated criminal damage.
It is believed the statue, which sits between High Street and Tollhouse Way, was targeted in the early hours of Friday morning.
CCTV is being recovered, and police officers are working closely with worshippers and management at the temple.
Sergeant Bill Gill, from the Smethwick Neighbourhood Team, said: “We understand that this attack has caused a lot of concern in the community, and we are working to understand the reasons behind it and identify whoever is responsible.
“Officers had already planned to be at the remembrance event which is happening tomorrow at the statue.
“I’d urge anyone with concerns to speak to the officers attending the event.”
If anyone has information on who is responsible, they can get in touch with the force directly on Live Chat between 8am and midnight, via 101 any time of day, or via Crimestoppers in complete confidence on 0800 555 111.
The statue is the first of its kind marking 100 years since the end of the First World War and commemorating the millions of men from the British Indian Army who served in both world wars.
Most had never visited the country they were fighting for but sacrificed their lives on the battlefield or afterwards.
Hundreds of people united in Smethwick's High Street last Sunday to watch history in the making as the bronze statue was revealed.
The monument was designed by Black Country sculpture Luke Perry, with costs covered by Guru Nanak Gurdwara Smethwick.
President of Guru Nanak Gurdwara Smethwick Jatinder Singh said he was extremely disappointed with the actions of the vandals but remained resolute.
He added: "There was some vandalism to the back wall which is very disappointing. The graffiti was cleaned off and the matter was reported to the police.
"Working with the council we won't allow this vandalism to undermine the very strong message created by this new monument and the overwhelmingly positive reaction to its unveiling.
"What makes this incident particularly distressing, is the complete disregard and lack of respect for the significance of the statue and inscriptions, installed recently to commemorate the losses felt by many South Asian families who lost their dear ones during the First World War and mark 100 years since the end of the Great War."