There is a famous World War I poster that shows a little girl innocently looking up at her father asking, "Daddy, what did you do during the Great War?" The bashful parent looks off into the distance, regret etched on his aquiline features.
OK, it's an obvious but effective piece of emotional blackmail and therefore excellent propaganda.
But the sentiment, a century or so on, holds true now. In years and decades to come, what will we tell our children about what we did while the entire globe was besieged by a rampant, vicious and indiscriminate enemy?
And it is a question which Prince William and Prince Harry will not be immune from having to answer.
Because, like much of their approach to public life, the Wales brothers' actions since the coronavirus crisis started have differed substantially.
Earlier this month the Royal Foundation, (now the sole province of William and Kate, the Duke and Duchess of Cambridge after last year's Sussex schism) put out a 103-word dull but worthy mission statement of sorts about what the couple are actually doing while they are holed up behind closed doors. On the list, providing "practical support to frontline responders and their families" and playing "a part in helping responders and their families with their mental health needs".
In recent weeks they have also visited a London emergency services call centre and undertaken a virtual school visit to speak to the children of essential workers. This week it was announced that William had taken on the patronage of the National Emergency Trust.
The couple are also reported to have been doing what charity patrons have been doing for generations – politely shaking down ultra-wealthy mates to support their causes. On Wednesday, the Daily Mail reported that the Cambridges "have teamed up with a string of wealthy benefactors to help charities who are supporting those leading the fight against coronavirus".
Let's be honest – this is hardly equivalent to King George VI and Queen Elizabeth resolutely staying in London as German bombs rained down on the beleaguered city.
But at least the Cambridges are flying their dependable, steadfast colours at full mast and doing what they do best – wearing mid-range British brands and gamely Doing Their Bit, albeit this time largely from what I'm guessing is their chintzy drawing room in Norfolk.
It isn't radical or wildly Instagram-worthy (a photo of a balding man making a phone call is hardly social media catnip) but they are filling a particular necessary function during this sort of catastrophe. They are brightly trying to rally the nation and are acting as something of a two-person British cheer squad. Pip pip old chums!
It is very tempting to wonder how the Sussexes would have responded to this global emergency if it had happened last year when they were still on the royal clock. Would they have baked homemade cupcakes with inspirational messages written in icing for nurses? Would they have rallied their coterie of billionaire mates (Oprah was a guest at their wedding; Harry attended Google Camp with a host of them last year) to help provide much-needed medical equipment to the struggling National Health Service? Would they have started a nightly Instagram live where they read to children?
No matter, I think we can assume it would have been creative, unusual and with a personal touch.
Sadly, we will never know because right now Harry and Meghan are believed to be in Los Angeles, having made a last-minute dash south via private jet from Canada before the border was closed last month.
For five long weeks they were not seen in public, having fired off their last Instagram post on March 31, the last day they were allowed to market themselves as Sussex Royal.
At the end of last week and then again yesterday, paparazzi shots of the couple volunteering with LA's Project Angel Food have emerged, the duo casually clad and wearing the mandatory masks.
Similarly, in the last week, Harry undertook a conference call in association with his patronage of Wellchild. Meghan also jumped on Zoom to connect with the Hubb Community Kitchen in London, which was founded by women after the devastating 2017 Grenfell fire, telling the group that she was "so proud" of their work.
What is interesting is that for two people so committed to public service it has taken weeks for the duo to assume something of a public role during this crisis. The obvious rejoinder is that they are now private citizens, no longer tethered to the institution of the monarchy and thus the inherent responsibility that implies.
Yet, the statement put out by Buckingham Palace after the Sandringham Summit outlined that they would continue to play a role with the organisations they officially support: "With The Queen's blessing, the Sussexes will continue to maintain their private patronages and associations … the Sussexes have made clear that everything they do will continue to uphold the values of Her Majesty."
However, between them they hold 20 patronages, which begs the question, just what have they done to hold up their end of that bargain?
They both have very significant roles when it comes to the Commonwealth and young people – why haven't they sent out an uplifting video message to those constituents and about the power of education during this time?
• Meghan Markle to give first TV interview since leaving royal life
• How the Queen proved Harry and Meghan wrong in four minutes
• Covid 19 coronavirus: Masked Harry and Meghan walk dogs amid LA lockdown
• Mystery of Meghan and Harry's final Instagram post
Why hasn't Meghan made a statement or talked about supporting the National Theatre and the arts during the time of Covid-19?
Both Harry and Meghan have made their love of Africa very clear, so at a time when the continent, where many countries only have four or five ventilators for tens of millions of people, is suffering, why have they not spoken up?
They might not have an Instagram account but surely this is a minor practical issue they could manage. After all, they only popped down to Stanford University to speak to experts about philanthropy in February – surely they could give them some pointers about how to get this sorted?
To be fair, on Thursday it was revealed that the extra $178,000 profit from sales of their 2018 wedding broadcast were being donated to Feeding Britain at Harry and Meghan's request. While this much-needed money will surely be a boon for the charity, it was raised long before the spectre of coronavirus.
More broadly, Harry and Meghan may no longer be officially royal but that does not abrogate them from playing a useful public role during this horrifying, trying time. No matter that they might not be able slap a crown on their branding, surely they still have a responsibility to speak up for the organisations they are meant to represent and publicly champion?
There are no easy answers or solutions to this entire, horrifying reality that all of us, royal and non-royal alike, are facing together. But there will come a time when we have to reconcile our actions or lack thereof during this crisis. All of us - no matter what continent we live on or whether there is an HRH in front of your name.
Daniela Elser is a royal expert and writer with more than 15 years experience working with a number of Australia's leading media titles. This article was first published on news.com.au.