The campaign seemed fairly standard and innocent: a simple fundraising challenge that encouraged meat-lovers to try to go without meat for just one month.
Yet within days of posting, the charity's social media was flooded with angry comments from livestock farmers, and their supporters, who said in their droves that they would withhold their donations.
Some even went so far as to say they would never support a cancer charity that ever promoted anything 'meat-free'.
Shortly after, Macmillan issued a statement: "We are sorry that it has caused upset, as this was never our intention and I can confirm that we will not be continuing to actively promote this event."
This apology sets a worrying precedent for companies who are increasingly looking to move towards more meat-free ideals. When animal farmers attack positive initiatives like Meat-Free March, they are silencing an opposing viewpoint and are trying to bully the public into eating meat.
The mainstream popularity of initiatives like Veganuary and Meat-Free Monday means that Macmillan would never have expected such an angry response to their unassuming campaign.
'Strong emotional blackmail'
Not only did farmers threaten to cancel their standing orders with the charity, but some also used strong emotional blackmail.
Farmers Weekly highlighted the 'mental anguish' that this campaign would cause to animal farmers, before referencing a tweet that read: "How to cause more mental health worries for our British Farmers. The rate of farming suicide is already high. Shame on you Macmillan!"
The high suicide rate in the agricultural community is a tragedy that urgently needs more government support in tackling. Poor mental health, stress and other leading causes must be addressed to save lives. But it does not help anyone to use this tragedy as leverage to push a certain agenda.
There is a current global shift for environmental and ethical reasons towards plant-based foods, and animal farmers can't place the responsibility of this shift onto a single charity - especially not by implying a single meat-free campaign could increase suicide rates.
Clearly, more needs to be done to help the farming community, particularly in supporting and helping those farmers who want to transition towards a more plant-based food system.
The community's anger towards a simple meat-free campaign shows that we need to do more to introduce animal farmers to the idea of becoming plant-based.
'Plant-based' or 'meat-free' should not be seen as threats to farmers, but as profitable and rewarding opportunities for them to diversify their produce.
Many workers in the meat industry are already on board and recognize meat-free as the future. Last year, Animal Rebellion blockaded Smithfield Market and its positive reception showed the changing tide from those working in the meat industry.
Despite the protest causing traders 'significant financial setback', workers like Steven Hall, a meat trader whose father and grandfather both worked at Smithfield, said: "To be honest, I think good on them. I've got two kids myself and I want the world to be safe for them in the future."
That positive sentiment is being echoed by farmers and meat traders around the world. There have been some incredible responses from Mercy For Animals' Transfarmation project, that empowers and supports the growing number of farmers who want to switch from raising animals to growing plants.
'Huge opportunity for growth'
Vegans and farmers have a lot to get angry about, together: intense, industrial factory-farms, cases of animal cruelty on UK farms, and the threat of climate change to our planet.
Our hopes for the future have a lot in common too, and needn't be seen as opposing sides: meat-free is creating exciting new profits for UK farmers, like the plant-based demand that's driving profits sky-high for pea protein.
So rather than getting angry and bullying meat-free initiatives, farmers should do what they do best: stand resilient, plow on, and work hard to diversify.
Meat-free foods represent a huge opportunity for growth and a secure future for the farmers, the animals, and our planet, too. So I hope there's still time for farmers to sign up for Macmillan's Meat-Free March.
*When contacted by Plant Based News, Macmillan did not comment on farmers threatening to withhold donations and said: "Meat Free March was first trialled at a small scale in 2019 and it yielded positive results for us so we decided to repeat it in 2020. However, it has not brought in the number of registrations and won’t reach the projected income we expected so we have decided to stop actively promoting the event. We can only be there for the growing number of people that urgently need our help thanks to wide range of fundraising activities we offer and we are hugely grateful to every single person to raises money for us."