The Duke of Sussex said life has "changed dramatically" as he marked what would have been the opening ceremony of the Invictus Games.
In a video posted on the event's Twitter account, Prince Harry urged the "Invictus family" to look out for each other and encouraged them to get involved with virtual activities over the coming days.
Harry said: "As we commemorate VE Day this weekend and pay tribute to the service and sacrifice of the entire Second World War generation, we should have also been gathering together in the Netherlands to kickstart the Invictus Games 2020 in The Hague.
"Life has changed dramatically for all of us since I was last in The Hague, but the IG 2020 team has done an incredible job to adapt so quickly to the situation, and they are busy putting plans in place for next year.
"The new dates will be shared with you very soon. I hope that all of those in the Invictus family are coping well and supporting each other through this challenging time."
Harry said he continues to hear "amazing" stories of families coming together over online platforms, but urged people to "look out for those that have gone quiet, or that are no longer visible on the chat sites".
He added: "You guys are the best at this, so I have no doubt that you're all rallying around and supporting one another.
"Although we can't be together in person, I'm really happy that there are plenty of virtual activities planned for this week, and I encourage you all to get involved if you can, because you never know, it might be fun and a change from the norm.
"Throughout this week, we will be seeing and hearing from many Invictus competitors, their experience and resilience in dealing with mental health challenges is something we could all learn lessons from."
He added the same can be said of "our incredible healthcare professionals" working hard to keep everyone safe.
Harry said the Invictus Games Foundation would host a virtual conference with international speakers and participants "sharing their thoughts and experience of resilience and why the Invictus spirit is so important".