They share a few things in common besides patriotism in their movies.
Manoj Kumar began his career as a mendicant in a song cameo in the 1957 Fashion-the song was a patriotic number, 'Dharti Ki God Mein', which uncannily put a patriotic imprint on Manoj right from the start! Akshay Kumar played a martial arts instructor in the 1990 Aaj in a one-scene cameo, which again defined his overall action-cum-martial-arts-aficionado image.
A small common trivia: while Manoj is himself a producer, his wife Shashi Goswami produced his film Kalyug Aur Ramayan (1987). Akshay's wife Twinkle Khanna too has produced many of his films, like Khatta Meetha, Action Replayy, Patiala House and Tees Maar Khan.
As for the patriotism, let us compare the two big stars of their respective eras.
We must understand that Manoj Kumar's family itself was a victim of Partition, spending several months in a refugee camp on the outskirts of Delhi. The horrors of those times and the hardships (Manoj had to walk miles and back just for milk for his family) left a huge mark on the actor-filmmaker. In the early '60s, having become a film actor, he decided to write the story of Bhagat Singh, and this film was ghost-directed by him and produced by his secretary Kewal P. Kashyap as Shaheed.
Manoj tasted blood with its success and when it won the President's Medal (the equivalent then of the National award) as well, Prime Minister Lal Bahadur Shastri asked him why he could not write a film on Shastri's slogan for the future of India, Jai Jawaan Jai Kisaan. That same day, on the way back to Mumbai by train, Manoj wrote the basic script of Upkar.
In short, that was the optimistic phase of India after Freedom, though cynicism and multiple problems had set in. Shaheed also came after the 1962 Indo-China war's trauma and the first war with Pakistan. Patriotism had been just reloaded.
With Akshay Kumar, it was all about current issues like terrorism and corruption. His first two patriotic films, Sainik (1993) and Ab Tumhare Hawale Watan Sathiyo (2004) were done as routine assignments that happened to have a patriotic theme. They failed at the box-office.
Manoj Kumar's film Upkar, about an idealistic farmer, not only was a blockbuster Golden Jubilee but established a new and unshakeable image for Manoj as 'Bharat Kumar' or, simply, 'Bharat'. It again won a National award, though Shastri was not alive to see his dream brought alive by Manoj.
After this, despite doing 'normal' films, most of which were also hits, Manoj became more synonymous with deshbhakti. In 1970, he wrote, starred in and again reportedly ghost-directed Yaadgar, a hit again. His next film as producer-writer-director, Purab Aur Pacchim, took up (in 1971) issues like migration for mammon and the clash between Indian and Western cultures. Then in 1974, he came up with a film on another important angle of patriotism-the basic human right of food, clothing and shelter in Roti Kapada Aur Makaan, not only the biggest hit of that year, but the film that began the multi-star trend.
His patriotism commercially peaked, ironically, with the jingoistic Salim-Javed-written potboiler, Kranti (1981). The movie had its moments, and with double irony, it became a huge hit. After this, Manoj creatively went off the mark with his satire on today's (lack of) values, Kalyug Aur Ramayan (which he wrote and acted in), the issue-based 1989 Clerk (a fiasco) and the delayed Jai Hind (1999), which saw his son Kunaal Goswami in the lead and could not even muster a decent release. All these movies got massive flak and put an end to his career as hero as well as filmmaker.
Conversely, in the era of the three Khans' supremacy Akshay Kumar has stood out (commercially and critically as well as in terms of reputation) more for his patriotic films than his other entertainers.
His 2007 Namastey London, was a smart contemporary avatar of Purab Aur Pacchim-the older film's cult number 'Hai Preet Jahan Ki Reet Sadaa', in which Manoj extols India and Indians to both the patriotic and the errant NRIs was replaced here by a monologue by Akshay Kumar to put arrogant Londoners who deride India in their place by serving them cold, hard facts about our achievements!
But Akshay's follow-up films were so diverse that, though Namastey London became a hit, there was no question of a similar deshbhakti tag going on the actor. A mediocre Khatta Meetha (exposing local corruption) was also a disaster in 2010.
Akshay too has touched on diverse aspects of desh-prem. The first of recent such films from him was, the 2014 Holiday-A Soldier Is Never Off Duty, in which he destroys a sleeper cell nexus of terrorists while on leave in Mumbai. This was followed by the gritty 2015 Baby (from Neeraj A Wednesday! Pandey), which highlighted all those anonymous, secret intelligence officers who fight against terrorism, with the clear knowledge that they will be disowned by India if caught or killed by the enemy.
The actor still says that these subjects coming to him are incidental and not planned. But when he reads the scripts, he is excited enough to back them as actor (Baby, Gabbar…Is Back) or also as co-producer (Holiday, Airlift). He feels blessed that he had the face, build and figure to etch such tough characters convincingly. Their realism, for him, is as enchanting as the larger-than-life entertainers he still loves to do, like Singh Is Bliing.
Their Patriotic Songs:
One area in which Akshay lags behind his senior is in the songs. Two songs-'Ashq Na Ho' (in the post-climax of Holiday when the soldiers are returning to the front) and 'Tu Bhoola Jise' (Airlift), both background numbers, are all that he has to show in this respect.
But Manoj Kumar's career is studded with cult classics like 'Mere Desh Ki Dharti' (Upkar), 'Ek Tara Bole' and 'Woh Khet Mein Milega' (Yaadgar), 'Hai Preet Jahaan Ke Reet Sadaa' and 'Dulhan Chali' (Purab Aur Pacchim), 'Mehengai Maar Gayi' (Roti Kapada Aur Makaan), 'Chana Zor Garam', 'Ab Ke Baras' and 'Kranti Kranti' (Kranti).
Then and Now
Manoj Kumar had his competence as an actor, his charisma and Midas touch as a star, and visionary skill as a writer and filmmaker. Till date, over three decades after his peak, he is still synonymous with patriotism in Hindi cinema, especially when Republic Day and Independence Day come up.
Akshay Kumar's Baby and Airlift, as per the needs of this era, have both fixed Republic Day week as the release date as "good dates for such films" (as Akshay terms them). His patriotism is more in tune with current trends and needs. Believing in mental and physical health, he has motivated his associates and fellow Indians by hosting shows on his pet passion-like on martial arts on the History channel and Fear Factor-Khatron Ke Khiladi, and even training women (of all classes and ages) for free in the art of self-defence. He also believes in inspiring Indians to do those small but important things to change lives, like pulling up those who spit on roads, for example.
In other words, while Manoj believes in preserving traditional Indian culture and values, Akshay is moulding fellow Indians to face the needs of the 21st century. Akshay Kumar is no replacement to Manoj Kumar, but they complement and complete each other!